Mail Server Error Codes Defined
Microsoft Exchange Server 2003 - NDR (Non-Delivery Report
|Explanation of Non-Delivery Report error codes for Exchange Server|
|4.2.2||The recipient has exceeded their mailbox limit. It could also be that the delivery directory on the Virtual server has exceeded its limit. (Default 22 MB)|
|4.3.1||Not enough disk space on the delivery server. Microsoft say this NDR maybe reported as out-of-memory error.|
|4.3.2||Classic temporary problem, the Administrator has frozen the queue.|
|4.4.1||Intermittent network connection. The server has not yet responded. Classic temporary problem. If it persists, you will also a 5.4.x status code error.|
|4.4.2||The server started to deliver the message but then the connection was broken.|
|4.4.6||Too many hops. Most likely, the message is looping.|
|4.4.7||Problem with a timeout. Check receiving server connectors.|
|4.4.9||A DNS problem. Check your smart host setting on the SMTP connector. For example, check correct SMTP format. Also, use square brackets in the IP address [18.104.22.168] You can get this same NDR error if you have been deleting routing groups.|
|4.6.5||Multi-language situation. Your server does not have the correct language code page installed.|
SMTP 500 reply code means an unrecognised command. You get this NDR
when you make a typing mistake when you manually try to send email via
More likely, a routing group error, no routing connector, or no suitable address space in the connector. (Try adding * in the address space)
This status code is a general error message in Exchange 2000. In fact Microsoft introduced a service pack to make sure now get a more specific code.
|5.1.x||Problem with email address.|
|5.1.0||Often seen with contacts. Check the recipient address.|
|5.1.1||Another problem with the recipient address. Possibly the user was moved to another server in Active Directory. Maybe an Outlook client replied to a message while offline.|
SMTP; 550 Host unknown. An error is triggered when the host name canít
be found. For example, when trying to send an email to bob@
[Example kindly sent in by Paul T.]
|5.1.3||Another problem with contacts. Address field maybe empty. Check the address information.|
|5.1.4||Two objects have the same address, which confuses the categorizer.|
|5.1.5||Destination mailbox address invalid.|
|5.1.6||Problem with homeMDB or msExchHomeServerName - check how many users are affected. Sometimes running RUS (Recipient Update Service) cures this problem. Mailbox may have moved.|
|5.1.7||Problem with senders mail attribute, check properties sheet in ADUC.|
|5.2.x||NDR caused by a problem with the large size of the email.|
|5.2.1||The message is too large. Else it could be a permissions problem. Check the recipient's mailbox.|
|5.2.2||Sadly, the recipient has exceeded their mailbox limit.|
|5.2.3||Recipient cannot receive messages this big. Server or connector limit exceeded.|
|5.2.4||Most likely, a distribution list or group is trying to send an email. Check where the expansion server is situated.|
|5.3.0||Problem with MTA, maybe someone has been editing the registry to disable the MTA / Store driver.|
|5.3.1||Mail system full. Possibly a Standard edition of Exchange reached the 16 GB limit.|
|5.3.2||System not accepting network messages. Look outside Exchange for a connectivity problem.|
|5.3.3||Remote server has insufficient disk space to hold email. Check SMTP log.|
|5.3.4||Message too big. Check limits, System Policy, connector, virtual server.|
|5.3.5||Multiple Virtual Servers are using the same IP address and port. See Microsoft TechNet article: 321721 Sharing SMTP. Email probably looping.|
|5.4.0||DNS Problem. Check the Smart host, or check your DNS. It means that there is no DNS server that can resolve this email address. Could be Virtual Server SMTP address.|
|5.4.1||No answer from host. Not Exchange's fault check connections.|
|5.4.3||Routing server failure. No available route.|
|5.4.4||Cannot find the next hop, check the Routing Group Connector. Perhaps you have Exchange servers in different Routing Groups, but no connector.|
|5.4.6||Tricky looping problem, a contact has the same email address as an Active Directory user. One user is probably using an Alternate Recipient with the same email address as a contact.|
|5.4.7||Delivery time-out. Message is taking too long to be delivered.|
Microsoft advise, check your recipient policy. SMTP address should be
|5.5.0||Underlying SMTP 500 error. Our server tried ehlo, the recipient's server did not understand and returned a 550 or 500 error. Set up SMTP logging.|
|5.5.2||Possibly the disk holding the operating system is full. Or could be a syntax error if you are executing SMTP from a telnet shell.|
|5.5.3||More than 5,000 recipients. Check the Global Settings, Message Delivery properties.|
|5.5.5||Wrong protocol version|
|5.6.3||More than 250 attachments.|
Permissions problem. For some reason the sender is not allowed to email
this account. Perhaps an anonymous user is trying to send mail to a
Check SMTP Virtual Server Access Tab. Try checking this box: Allow computers which successfully authenticate to relay
User may have a manually created email address that does not match a System Policy.
|5.7.2||Distribution list cannot expand and so is unable to deliver its messages.|
|5.7.3||Check external IP address of ISA server. Make sure it matches the SMTP publishing rule.|
|5.7.4||Extra security features not supported. Check delivery server settings|
|5.7.5||Cryptographic failure. Try a plain message with encryption.|
|5.7.6||Certificate problem, encryption level maybe to high.|
|5.7.7||Message integrity problem.|
|ATRN||Authenticated TURN.||RFC 2645|
|BDAT||Binary data.||RFC 3030|
|BURL||Remote Content.||RFC 4468|
|EHLO||Extended Hello.||RFC 2821|
|ETRN||Extended Turn.||RFC 1985|
|NOOP||No operation||RFC 2821|
|ONEX||One message transaction only.|
|SAML||Send and mail.||RFC 821|
|SOML||Send or mail.||RFC 821|
|SUBMITTER||SMTP Responsible Submitter.||RFC 4405|
SMTP Reply Codes:
|211||System status, or system help reply.|
|220||Domain service ready.
Ready to start TLS.
|221||Domain service closing transmission channel.|
|250||OK, queuing for node node started.
Requested mail action okay, completed.
|251||OK, no messages waiting for node node.
User not local, will forward to forwardpath.
|252||OK, pending messages for node node started.
Cannot VRFY user (e.g., info is not local), but will take message for this user and attempt delivery.
|253||OK, messages pending messages for node node started.|
|354||Start mail input; end with <CRLF>.<CRLF>.|
|355||Octet-offset is the transaction offset.|
|421||Domain service not available, closing transmission channel.|
|432||A password transition is needed.|
|450||Requested mail action not taken: mailbox unavailable.
ATRN request refused.
|451||Requested action aborted: local error in processing.
Unable to process ATRN request now
|452||Requested action not taken: insufficient system storage.|
|453||You have no mail.|
|454||TLS not available due to temporary reason.
Encryption required for requested authentication mechanism.
|458||Unable to queue messages for node node.|
|459||Node node not allowed: reason.|
|500||Command not recognized: command.
|501||Syntax error, no parameters allowed.|
|502||Command not implemented.|
|503||Bad sequence of commands.|
|504||Command parameter not implemented.|
|521||Machine does not accept mail.|
|530||Must issue a STARTTLS command first.
Encryption required for requested authentication mechanism.
|534||Authentication mechanism is too weak.|
|538||Encryption required for requested authentication mechanism.|
|550||Requested action not taken: mailbox unavailable.|
|551||User not local; please try forwardpath.|
|552||Requested mail action aborted: exceeded storage allocation.|
|553||Requested action not taken: mailbox name not allowed.|