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Electronic mail non-delivery reports in Exchange Online

• Article
• 04/05/2022
• 27 minutes to read

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When in that location's a problem delivering an email message that you sent, Microsoft 365 or Office 365 sends an email to let y'all know. The email you receive is a delivery status notification, also known as a DSN or bounce bulletin. The most mutual type is called a non-delivery study (NDR) and they tell you that a message wasn't delivered. Non-delivery tin can exist caused by something as elementary as a typo in an email address. NDRs include an error lawmaking that indicates why your email wasn't delivered, solutions to assistance you become your email delivered, a link to more help on the web, and technical details for administrators. Detect out What'due south included in an NDR?.

Observe my NDR code and get help delivering my email

The following table contains the NDR codes (also called enhanced status codes) for the most common bounce messages and NDRs that you might encounter in Exchange Online.

NDR code	Description	Possible crusade	Additional information
432 iv.3.2	STOREDRV.Evangelize; recipient thread limit exceeded	The recipient mailbox's ability to accept letters is being throttled because information technology's receiving too many messages too quickly. This is done and then a single recipient's mail processing doesn't unfairly touch on other recipients sharing the same mailbox database.	For more than information about this by-design throttling, meet Store Driver Fault Isolation Improvements in Exchange 2010 SP1.
4.iv.316	Connectedness refused [Message=Socket fault lawmaking 10061]	Microsoft 365 or Office 365 is trying to ship a message to an email server outside of Microsoft 365 or Office 365, but attempts to connect to information technology are failing due to a network connection issue at the external server's location.	This error almost always indicates an issue with the receiving server or network outside of Microsoft 365 or Role 365. The error should also include the IP address of the server or service that's generating the error, which you can use to identify the political party responsible for fixing this.
4.4.7	Message expired	The message in the queue has expired. The sending server tried to relay or deliver the message, merely the action wasn't completed before the message expiration time occurred. This message can also indicate that a message header limit has been reached on a remote server, or some other protocol time-out occurred while communicating with the remote server.	This message usually indicates an issue on the receiving server. Check the validity of the recipient address, and determine if the receiving server is configured correctly to receive messages. You might have to reduce the number of recipients in the bulletin header for the host well-nigh which you're receiving this error. If you send the message again, it's placed in the queue over again. If the receiving server is available, the message is delivered. For more information, see Gear up email delivery issues for error code iv.4.7 in Exchange Online.
4.v.iii	Also many recipients	The message has more than 200 SMTP envelope recipients from the same domain.	An envelope recipient is the original, unexpanded recipient that's used in the RCPT TO command to transmit the message between SMTP servers. When this mistake is returned by Microsoft 365 or Function 365, the sending server must break upwards the number of envelope recipients into smaller chunks (chunking) and resend the message.
4.7.26	Admission denied, a message sent over IPv6 [2a01:111:f200:2004::240] must pass either SPF or DKIM validation, this message is not signed	The sending message sent over IPv6 must pass either SPF or DKIM.	For more data, see Back up for anonymous inbound email messages over IPv6.
iv.7.321	starttls-not-supported: Destination mail server must back up TLS to receive mail service.	DNSSEC checks take passed, yet upon connectedness, destination mail server doesn't respond to the STARTTLS command. The destination server responds to the STARTTLS control, but the TLS handshake fails.	This bulletin usually indicates an outcome on the destination email server. Check the validity of the recipient address. Determine if the destination server is configured correctly to receive the messages.
four.7.322	document-expired: Destination post server'south document is expired.	DNSSEC checks have passed, notwithstanding upon establishing the connectedness, the destination mail server provides a certificate that is expired.	A valid X.509 document that isn't expired must be presented. X.509 certificates must exist renewed after their expiration, commonly annually.
iv.7.323	tlsa-invalid: The domain failed DANE validation.	Records are DNSSEC authentic, just one or multiple of these scenarios occurred: The destination post server'south certificate doesn't match with what is expected per the authentic TLSA record. Accurate TLSA tape is misconfigured. Destination domain is being attacked. Whatsoever other DANE failure.	This message usually indicates an issue on the destination email server. Check the validity of recipient accost and make up one's mind if the destination server is configured correctly to receive messages. For more information, meet DANE protocol: updates and operational guidance
4.7.324	dnssec-invalid: Destination domain returned invalid DNSSEC records	The destination domain indicated it was DNSSEC-accurate, but Exchange Online wasn't able to verify information technology equally DNSSEC-authentic.	For more information, see Overview of DNSSEC.
four.seven.325	certificate-host-mismatch: Remote certificate MUST have a mutual name or subject alternative name matching the hostname (DANE)	This happens when the presented certificate identities (CN and SAN) of a destination SMTP target host don't match any of the domains or MX host.	This message usually indicates an issue on the destination e-mail server. Cheque the validity of recipient address and determine if the destination server is configured correctly to receive letters. For more information, encounter How SMTP DNS-based Authentication of Named Entities (DANE) works to secure email communications.
four.vii.500-699	Access denied, please try again later	Suspicious activity has been detected and sending has been temporarily restricted for further evaluation.	If this activity is valid, this restriction will exist lifted soon.
4.vii.850-899	Admission denied, please try again later	Suspicious activity has been detected on the IP in question, and it has been temporarily restricted while it'south being farther evaluated.	If this activity is valid, this restriction will be lifted presently.
5.0.350	Generic mistake, x-dg-ref header is too long, or Requested action not taken: policy violation detected (AS345)	5.0.350 is a generic catch-all mistake code for a wide variety of non-specific errors from the recipient's email organization. The specific x-dg-ref header is too long message is related to Rich Text formatted messages. The specific Requested action not taken: policy violation detected (AS345) message is related to nested attachments.	For more information, meet Prepare email delivery issues for fault code 550 5.0.350 in Exchange Online.
5.i.0	Sender denied	A common cause of this NDR is when you utilise Microsoft Outlook to save an email message as a file, so someone opened the message offline and replied to it. The message property simply preserves the legacyExchangeDN attribute when Outlook delivers the message, and therefore the lookup could fail.	Either the recipient address is incorrectly formatted, or the recipient couldn't exist correctly resolved. The first step in resolving this error is to check the recipient address, and transport the message once again. For more information, run across Gear up email delivery issues for fault code 5.1.0 in Commutation Online.
5.1.ane	Bad destination mailbox address	This failure might exist caused past the following conditions: The recipient's e-mail address was entered incorrectly past the sender. No recipient's exists in the destination email arrangement. The recipient's mailbox has been moved and the Outlook recipient cache on the sender's estimator hasn't updated. An invalid legacy domain name (DN) exists for the recipient's mailbox Active Directory Domain Service.	This error typically occurs when the sender of the message incorrectly enters the email address of the recipient. The sender should cheque the recipient's email accost and send again. This error tin can also occur if the recipient email address was correct in the by but has changed or has been removed from the destination email system. If the sender of the bulletin is in the same organization as the recipient, and the recipient'southward mailbox still exists, make up one's mind whether the recipient'southward mailbox has been relocated to a new email server. If this is the instance, Outlook might non have updated the recipient cache correctly. Instruct the sender to remove the recipient'south accost from sender'due south Outlook recipient cache and then create a new message. Resending the original message will result in the same failure. For more data, see Fix email delivery problems for error code 5.1.ane through 5.1.twenty in Exchange Online.
5.1.8	Access denied, bad outbound sender	The account has been blocked for sending too much spam. Typically, this problem occurs because the account has been compromised (hacked) by phishing or malware.	For more data, see Prepare electronic mail delivery bug for error code 5.1.viii in Substitution Online.
5.one.10	Recipient not institute	The recipient's <SMTP Accost> wasn't found by SMTP address lookup.	For more than information, see Ready electronic mail delivery issues for error lawmaking 550 v.1.x in Exchange Online.
five.one.90	Your message tin can't be sent because you've reached your daily limit for message recipients	The sender has exceeded the recipient charge per unit limit every bit described in Sending limits.	This could bespeak the account has been compromised and is beingness used to send spam. For more data, run into How to determine whether your account has been compromised.
5.2.2	Submission quota exceeded	The sender has exceeded the recipient rate limit or the message rate limit as described in Sending limits.	This could bespeak the account has been compromised and is being used to send spam. For more data, encounter How to determine whether your account has been compromised.
5.2.121	Recipient's per hr message receive limit from specific sender exceeded.	The sender has exceeded the maximum number of messages they're allowed to send per hour to a specific recipient in Exchange Online.	The automated mailer or sender should try once again after, and reduce the number of messages they send per hour to a specific recipient. This limit helps protect Microsoft 365 or Office 365 users from speedily filling their inboxes with a big number of messages from errant automated notification systems or other single-sender mail storms.
five.2.122	Recipient's per hour message receive limit exceeded.	The Microsoft 365 or Office 365 recipient has exceeded the number of letters they tin can receive per hour from all senders.	The automatic mailer or sender should try once again later on, and reduce the number of messages they send per 60 minutes to a specific recipient. This limit helps protect Microsoft 365 and Office 365 users from rapidly filling their inboxes with a large number of messages from errant automated notification systems or other postal service storms.
five.3.190	Journaling on-premises messages to Microsoft 365 or Office 365 not supported when Journaling Archive is disabled.	Journaling on-bounds messages to Microsoft 365 or Role 365 isn't supported for this organization considering they haven't turned on Journaling Archive in their settings.	A journaling rule is configured in the organization's on-premises environment to periodical on-premises letters to Microsoft 365 or Office 365, but Journaling Archive is disabled. For this scenario to work, the organisation'southward Function 365 administrator should either enable Journaling Annal or change the journaling rule to journal messages to a different location.
5.4.1	Relay Admission Denied	The mail server that's generating the error doesn't accept mail for the recipient'due south domain. This error is caused by mail server or DNS misconfiguration.	For more information, see Fix email commitment bug for error lawmaking 5.4.ane in Exchange Online.
five.four.1	Recipient accost rejected: Access denied	The recipient'due south address doesn't exist.	For more information, see Use Directory Based Border Blocking to reject messages sent to invalid recipients.
5.four.6 or 5.4.xiv	Routing loop detected	A configuration error has caused an email loop. 5.4.half-dozen is generated by on-premises Substitution server (you'll encounter this code in hybrid environments). 5.4.14 is generated past Exchange Online. By default, after xx iterations of an e-mail loop, Exchange interrupts the loop and generates an NDR to the sender of the message.	This error occurs when the delivery of a bulletin generates another message in response. That message so generates a third message, and the process is repeated, creating a loop. To help protect confronting exhausting system resources, Exchange interrupts the mail loop after 20 iterations. Mail loops are typically created considering of a configuration error on the sending post server, the receiving mail server, or both. Check the sender's and the recipient'southward mailbox rules configuration to determine whether automatic message forwarding is enabled. For more than data, see Prepare e-mail delivery issues for error lawmaking v.4.six or five.4.14 in Exchange Online.
v.4.300	Message expired	The email took likewise long to be successfully delivered, either because the destination server never responded or the sent bulletin generated an NDR error and that NDR couldn't exist delivered to the original sender.
5.v.0	550 five.v.0 Requested activity not taken: mailbox unavailable	The recipient'south <SMTP Address> domain is @hotmail.com or @outlook.com and information technology wasn't institute past SMTP address lookup.	Like to 550 5.1.10. For more data, see Fix e-mail commitment bug for error code 550 5.ane.ten in Substitution Online.
5.six.11	Invalid characters	Your electronic mail program added invalid characters (blank line feed characters) into a message you sent.	For more than information, see Ready electronic mail delivery bug for mistake code 5.six.11 in Exchange Online.
5.7.1	Commitment not authorized	The sender of the bulletin isn't immune to send letters to the recipient.	This error occurs when the sender tries to send a message to a recipient but the sender isn't authorized to practice this. This oftentimes occurs when a sender tries to send messages to a distribution group that has been configured to accept messages only from members of that distribution group or other authorized senders. The sender must asking permission to send messages to the recipient. This fault can also occur if an Exchange transport rule rejects a message considering the message matched weather that are configured on the transport rule. For more than information, run into Fix email commitment problems for error code 5.7.i in Exchange Online.
v.vii.one	Unable to relay	The sending email organisation isn't allowed to transport a message to an e-mail system where that electronic mail system isn't the final destination of the message.	This mistake occurs when the sending email system tries to send an anonymous bulletin to a receiving email system, and the receiving email system doesn't accept messages for the domain or domains specified in i or more of the recipients. The post-obit are the most common reasons for this error: A third party tries to utilise a receiving email system to send spam, and the receiving e-mail arrangement rejects the attempt. By the nature of spam, the sender's electronic mail address might have been forged, and the resulting NDR could have been sent to the unsuspecting sender'due south e-mail accost. It's difficult to avoid this situation. An MX record for a domain points to a receiving email system where that domain isn't accepted. The ambassador responsible for the specific domain name must right the MX record or configure the receiving email organisation to accept messages sent to that domain, or both. A sending electronic mail system or client that should use the receiving email organisation to relay letters doesn't have the correct permissions to practice this. For more information, run across Fix electronic mail commitment issues for error code 5.seven.i in Substitution Online.
5.7.1	Client was not authenticated	The sending email organization didn't cosign with the receiving electronic mail organisation. The receiving electronic mail system requires authentication before message submission.	This mistake occurs when the receiving server must be authenticated before message submission, and the sending electronic mail system hasn't authenticated with the receiving electronic mail system. The sending email arrangement administrator must configure the sending e-mail arrangement to authenticate with the receiving email organisation for commitment to exist successful. For more data, run into Fix e-mail delivery issues for mistake code 5.seven.one in Exchange Online.
5.7.12	Sender was not authenticated past organisation	The sender's bulletin is rejected considering the recipient address is gear up to reject messages sent from exterior of its system. Only an e-mail admin for the recipient's system tin change this.	For more data, see Fix email delivery problems for fault code v.7.12 in Exchange Online.
five.7.23	The bulletin was rejected because of Sender Policy Framework violation	The destination email system uses SPF to validate inbound mail, and there's a trouble with your SPF configuration.	For more than data, come across Set electronic mail delivery problems for error code v.vii.23 in Exchange Online.
5.7.57	Client was not authenticated to ship anonymous mail during Postal service FROM	You configured an application or device to send (relay) electronic mail messages in Microsoft 365 or Role 365 using the smtp.office365.com endpoint, and there's a problem with the configuration of the application or device.	For more information, see Fix email delivery issues for mistake code 5.7.57 in Commutation Online.
5.7.64	TenantAttribution; Relay Access Denied	Yous use an inbound connector to receive letters from your on-premises email environs, and something has changed in your on-premises environs that makes the inbound connector's configuration incorrect.	For more than information, see Fix email delivery issues for error code five.7.64 in Exchange Online.
v.7.124	Sender not in allowed-senders list	The sender doesn't have permission to send to the distribution group because the sender isn't in the grouping's allowed-senders list. Depending how the group is set up upwards, even the grouping's owner might demand to be added to the allowed sender list in order to send messages to the group.	For more information, meet Fix email delivery issues for error code 5.7.124 in Commutation Online.
v.7.133	Sender not authenticated for group	The recipient address is a group distribution listing that is fix to decline messages sent from exterior of its organization. Only an e-mail admin for the recipient'due south organization or the grouping owner can change this.	For more information, see Set e-mail delivery issues for mistake code 5.seven.133 in Exchange Online.
v.7.134	Sender was non authenticated for mailbox	The recipient address is a mailbox that is set up to reject letters sent from outside of its organization. Merely an email admin for the recipient'south organization can change this.	For more than information, run across Fix email delivery issues for fault code 5.7.134 in Exchange Online.
5.7.13 or 135	Sender was not authenticated for public folder	The recipient accost is a public folder that is prepare up to reject messages sent from outside of its organization. Simply an email admin for the recipient's arrangement can modify this.	For more information, see Fix email delivery bug for error lawmaking 5.vii.13 or 5.seven.135 in Substitution Online.
five.vii.136	Sender was not authenticated	The recipient address is a mail user that is set up to reject messages sent from outside of its organization. But an email admin for the recipient'south system can change this.	For more information, come across Fix email delivery problems for error code 5.7.136 in Exchange Online.
5.seven.25	Admission denied, the sending IPv6 address [2a01:111:f200:2004::240] must have a opposite DNS record	The sending IPv6 address must have a opposite DNS record in order to transport e-mail over IPv6.	For more than data, see Support for anonymous inbound email messages over IPv6.
five.7.321	starttls-not-supported: Destination mail service server must support TLS to receive postal service.	DNSSEC checks have passed, however upon connection the destination mail server doesn't respond to the STARTTLS control. The destination server responds to the STARTTLS command, but the TLS handshake fails.	This message normally indicates an upshot on the destination mail server. Check the validity of the recipient address and determine if the destination server is configured correctly to receive messages.
5.7.322	document-expired: Destination mail server'south certificate is expired.	DNSSEC checks take passed, yet upon establishing the connection the destination mail server provides a certificate that is expired.	A valid 10.509 certificate that isn't expired must be presented. 10.509 certificates must be renewed after their expiration, normally annually.
5.7.323	tlsa-invalid: The domain failed DANE validation.	Records are DNSSEC authentic but 1 or multiple of these things occurred: The destination mail server'south certificate doesn't match with what is expected per the authentic TLSA tape. Accurate TLSA record is misconfigured. Destination domain is existence attacked. The document start engagement is in the future. Any other DANE failure.	This message usually indicates an issue on the destination postal service server. Check the validity of the recipient address and decide if the destination server is configured correctly to receive messages. For more information about DANE, run into: https://datatracker.ietf.org/doc/html/rfc7671.|
5.seven.324	dnssec-invalid: Destination domain returned invalid DNSSEC records	The destination domain indicated it was DNSSEC-accurate but Exchange Online wasn't able to verify information technology as DNSSEC-authentic.	For more information about DNSSEC, run into: Overview of DNSSEC.
5.7.325	certificate-host-mismatch: Remote document MUST have a mutual proper noun or field of study alternative proper name matching the hostname (DANE)	This happens when the presented document identities (CN and SAN) of a destination SMTP target host don't match any of the domains or MX host.	This message usually indicates an event on the destination email server. Check the validity of recipient accost and determine if the destination server is configured correctly to receive letters. For more information, see How SMTP DNS-based Authentication of Named Entities (DANE) works to secure email communications.
5.7.501	Access denied, spam corruption detected	The sending account has been banned due to detected spam activity.	For details, see Fix email delivery issues for mistake code 451 v.7.500-699 (ASxxx) in Substitution Online. Verify that any account issues take been resolved, and reset its credentials. To restore this account'southward ability to transport postal service, contact back up through your regular channel.
5.seven.502	Access denied, banned sender	The sending account has been banned due to detected spam activity.	Verify that whatsoever account issues have been resolved, and reset its credentials. To restore this account'south ability to send postal service, delight contact support through your regular channel.
5.7.503	Access denied, banned sender	The sending account has been banned due to detected spam activity.	Verify that any account problems have been resolved, and reset its credentials. To restore this account'due south power to send postal service, please contact back up through your regular channel.
5.7.504	[email@contoso.com]: Recipient accost rejected: Access denied	The recipient accost that you're attempting to contact isn't valid.	Verify the recipient's e-mail address, and effort over again.
5.7.505	Access denied, banned recipient	The recipient that yous're attempting to contact isn't valid.	If you experience this is in error, contact support.
5.7.506	Access Denied, Bad HELO	Your server is attempting to innovate itself (HELO according to RFC 821) every bit the server information technology's trying to connect to, rather than its own fully qualified domain name.	This isn't immune, and it's characteristic of typical spambot behavior.
5.7.507	Admission denied, rejected past recipient	The IP that you lot're attempting to send from has been blocked past the recipient's organization.	Contact the recipient in order to resolve this result.
5.7.508	Access denied, [$SenderIPAddress] has exceeded permitted limits within $range range	The sender'southward IPv6 range has attempted to send likewise many messages in as well short a time period.	Not applicative
five.vii.509	Admission denied, sending domain [$SenderDomain] does not pass DMARC verification	The sender'south domain in the 5322.From address doesn't pass DMARC.	Not applicable
5.7.510	Access denied, [contoso.com] does not accept electronic mail over IPv6	The sender is attempting to transmit a bulletin to the recipient over IPv6, but the recipient doesn't have electronic mail letters over IPv6.	Not applicable
5.7.511	Access denied, banned sender	The IP that you're attempting to send from has been banned.	To delist the address, email delist@messaging.microsoft.com and provide the full NDR code and IP address to delist. For more than information, see Utilize the delist portal to remove yourself from the blocked senders list.
5.seven.512	Access denied, message must exist RFC 5322 section 3.6.two compliant	Message was sent without a valid "From" email address.	Part 365 only. Each message must contain a valid email accost in the "From" header field. Proper formatting of this address includes angle brackets around the email address, for example, <security@contoso.com>. Without this address Microsoft 365 or Office 365 will decline the message.
5.7.513	Service unavailable, Client host [$ConnectingIP] blocked by $recipientDomain using Customer Block list (AS16012607)	The recipient domain has added your sending IP address to its custom blocklist.	The domain that received the email has blocked your sender'south IP address. If you remember your IP address has been added to the recipient domain's custom blocklist in error, you need to contact them directly and enquire them to remove it from the blocklist.
5.7.606-649	Access denied, banned sending IP [IP1.IP2.IP3.IP4]	The IP that you lot're attempting to transport from has been banned.	Verify that you're following the best practices for e-mail deliverability, and ensure your IPs' reputations haven't been degraded as a result of compromise or malicious traffic. If you believe you lot're receiving this message in fault, you lot can use the self-service portal to asking to exist removed from this list. For more information, encounter Utilize the delist portal to remove yourself from the blocked senders list.
v.vii.700-749	5.7.705 Access denied, tenant has exceeded threshold, 5.7.708 Admission denied, traffic not accepted from this IP	The majority of traffic from this tenant has been detected every bit suspicious and has resulted in a ban on sending ability for the tenant.	Ensure that whatever compromises or open relays accept been resolved, and so contact support through your regular aqueduct. For more information, see Fix email delivery issues for fault codes 5.7.700 through five.7.750 in Exchange Online.
five.7.750	Service unavailable. Client blocked from sending from unregistered domains	A suspicious number of messages from unprovisioned domains is coming from this tenant.	Add together and validate whatsoever and all domains that you apply to ship email from Microsoft 365 or Office 365. For more information, see Fix e-mail delivery issues for error codes five.7.700 through 5.7.750 in Exchange Online.
n/a	The message can't be submitted because the sender'southward submission quota was exceeded	The user account has exceeded the recipient rate limit (10,000 recipients per day).	The business relationship has likely been compromised. For more information, run into Fix email delivery issues for error 'the sender's submission quota was exceeded' in Exchange Online.

Run non-delivery study diagnostics

Note

This characteristic requires a Microsoft 365 administrator account. This feature isn't available for Microsoft 365 Government, Microsoft 365 operated by 21Vianet, or Microsoft 365 Germany.

To learn more most the description of the non-delivery report (NDR), possible cause, and solution by running the following NDR diagnostic, you tin can run an automatic diagnostic. Brand sure you get the NDR code or status lawmaking from the undeliverable/non-delivery report.

To run the diagnostic check, select the following push:

A flyout page opens in the Microsoft 365 admin center. Paste the NDR code or fault message, and then select Run Tests.

What's included in an NDR?

Exchange NDRs are designed to exist easy to read and understand by email users and administrators. There are a couple of dissimilar formats for NDRs. The newest style NDR contains a problem clarification in everyday linguistic communication, along with steps to fix it. The post-obit effigy shows the format for this blazon of NDR.

Information provided in the newest fashion NDRs is designed to assist the typical email user solve their trouble immediately. When that isn't possible, the NDR provides details for administrators and also a link to more help on the web. The following fields appear in the newest Office 365 NDRs.

Field	Description
Function 365 logo	This indicates that Microsoft 365 or Part 365 generated the NDR. The logo doesn't hateful that Microsoft 365 or Part 365 was responsible for the error. This tells which messaging endpoints or services are involved in the electronic mail transaction, which isn't always articulate in older fashion NDRs.
Cause	This department provides the reason that the message wasn't delivered.
Prepare-it owner indicator	This section provides an at-a-glance view of the issue and who needs to gear up it. The image shows the three basic parties in a Microsoft 365 or Office 365 email transaction: the sender, Microsoft 365 or Office 365, and the recipient. The area marked in red is where the problem commonly must be fixed.
How to prepare it	This section is designed for the finish-user or the email sender who receives the NDR. Information technology explains how to fix the issue.
More info for email admins	This section provides a detailed explanation of the problem and solution forth with technical details and a link to a web-based article that has detailed reference data.
Bulletin hops	This section contains times and system references for the message, which allows an admin to follow the message's hops or server-to-server path. With this info, an admin might apace spot problems between message hops.

For NDRs that don't accept the latest format, the information might exist separated into 2 sections: User data, and Diagnostic data for administrators. The following figure shows the format for one type of Exchange Online NDR.

User information

The user information department appears kickoff in some NDRs, and the main purpose is to provide a summary nearly what went wrong. The text is designed to assist the message sender make up one's mind why the message was rejected and, if possible, how to resend the bulletin successfully. The email accost of each recipient is listed, and the reason for the failure is included in the space below the recipient'southward e-mail address. The name of the mail service server that rejected the message might also be included in this section.

Diagnostic data for administrators

The Diagnostic information for administrators section provides deeper technical data to help administrators troubleshoot the message delivery problem. It contains detailed information most the specific error that occurred during delivery of the bulletin, the server that generated the NDR, and the server that rejected the message. This section uses the following format:

              Diagnostic information for administrators Generating server: <server name>           <rejected recipient>           <remote server>            <enhanced status code>  <SMTP response> Original message headers <message header fields>                          

Field	Description
Generating server	This field indicates the name of the SMTP mail server that created the NDR. If no remote server is listed below the sender's electronic mail address, the generating server is also the server that rejected the original email message. When the remote mail server acknowledges and accepts the message, but later rejects the message, for instance, because of content restrictions, the remote server generates the NDR. If the remote mail server never acknowledges and never accepts the bulletin, the sending server in Commutation Online generates the NDR.
<Rejected recipient>	This value is the electronic mail accost of the recipient. If commitment failed to more than than one recipient, the e-mail address for each recipient is listed. The following information is also included for each failed recipient: Field Description
<Remote server>	This value is the name of the mail server that rejected the bulletin. If the original bulletin is successfully acknowledged by the receiving server, just is afterwards rejected, the remote server value isn't populated.
<Enhanced condition code>	This value is assigned by the mail service server that rejected the original bulletin and indicates why the message was rejected. These codes are defined in RFC 3463, and use the format abc x.y.z, where the placeholder values are integers. For example, a five.ten.ten code indicates a permanent error, and a 4.10.x code indicates a temporary error. Although the enhanced status code is oftentimes generated past an external post server, Exchange Online uses the enhanced condition code value to determine the text to display in the user information department.
<SMTP response>	This value is returned by the postal service server that rejected the original message. This text provides an explanation for the enhanced status code value. The text is e'er presented in U.s.a.-ASCII format.
Original message headers	This section contains the message header fields of the rejected message. These header fields can provide useful diagnostic information, such every bit the path that the message took before information technology was rejected, or whether the To field value matches the rejected recipient value.

How to interpret an Commutation NDR

Hither'due south an example. Suppose you receive an Exchange NDR that contains the post-obit information:

              Delivery has failed to these recipients or groups: ronald@contoso.com Your bulletin wasn't delivered due to a permission or security issue. Information technology might have been rejected by a moderator, the accost might only accept electronic mail from sure senders, or another brake might be preventing commitment. The post-obit organisation rejected your bulletin: post.contoso.com. Diagnostic information for administrators: Generating server: alpineskihouse.com ronald@contoso.com postal service.contoso.com #<exchange.contoso.com #5.7.1 smtp;530 v.7.ane Client was non authenticated> #SMTP# Original message headers: ...                          

From the user information section, you tin can make up one's mind that the recipient is Ronald Slattery, and that the message was rejected by the mail service server mail.contoso.com, which isn't an Exchange Online or Exchange Online Protection postal service server.

From the Diagnostic information for administrators department, you can see that alpineskihouse.com attempted to connect to the server mail.contoso.com to deliver the message to the recipient ronald@contoso.com. Withal, mail.contoso.com responded with the error 530 5.vii.1 Client was non authenticated. Even though bigfish.com generated the NDR, post.contoso.com actually rejected the bulletin, so the administrators at contoso.com are responsible for agreement and fixing the problem. This particular error indicates that the server post.contoso.com is configured not to take anonymous e-mail from the Internet.

Although the Original bulletin headers are omitted from this example due to their length and complexity, y'all can typically extract useful information from the following header fields:

• To: This field might be helpful if the email address was mistyped.

• Received: These fields can tell yous what the path was for the bulletin, and the last hop that generated the commitment status notification if it isn't easy to tell from the Generating server value in the NDR.

• Received-SPF: If this value is anything other than pass, bank check the Sender Policy Framework (SPF) DNS tape for your domain. For more than information, come across Add or edit custom DNS records.

Even so need help with NDRs or other condition notifications?

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Source: https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/non-delivery-reports-in-exchange-online/non-delivery-reports-in-exchange-online