Code |
En. Code |
Error Phrase |
Description |
Remedy Instructions |
500 |
5.5.1 |
Command unrecognized |
The SMTP command currently used was unrecognized or is not supported by the SMTP service. |
Review the syntax of the last command and try again. |
Another possibility is that you are trying to use telnet and the telnet connection to your server is not allowed. Check the settings in administration console: Mail Service – Security – Advanced. |
501 |
5.5.2 |
Domain name required |
Sender has no domain specified (usually in MAIL FROM). |
Specify the sender's domain name and try again. |
The problem will be with user's email client, not your server. The email client configuration is probably not supplied with a domain name. |
501 |
5.5.2 |
Unbalanced |
SMTP session syntax invalid (usually unbalanced brackets). |
Check the syntax of the last command and the configuration of corresponding .dat files. |
501 |
5.5.4 |
Syntax error in parameters scanning |
Common syntax error. You probably mis-typed last command or last string is invalid. |
Check the syntax of the last command. |
501 |
5.5.1 |
HELO/EHLO requires domain address |
Usually when there was blank or invalid string sequence after HELO/EHLO command. |
Retry the SMTP greeting with correct HELO/ELHO command. |
501 |
5.0.0 |
Authentication canceled |
The process of authentication was canceled for any reason. |
Restart the authentication process by using proper command. |
501 |
5.7.1 |
Message is too long |
Exceeded message size limit |
Review settings of limits on server/domain/user levels. |
501 |
5.7.1 |
Permission denied |
1) Username given in AUTH differs from sender in mail FROM |
1) Disable this – check in administration console: Mail – Security – Advanced – Reject if SMTP AUTH different from sender. |
2) Message submission is active and not used by local sender, or unauthenticated access to submission port |
2) Local senders has to use submission port or disable this setting using the C_Mail_SMTP_Delivery_MessageSubmission API variable. |
3) Milter filter returns error in envfrom stage |
3) Check used filter. |
501 |
5.7.1 |
Sender domain must exist |
MX record of sender's domain was not found |
Disable this – check in administration console: Mail – Security – DNS – Reject if originator's domain doesn't exist or disable the C_Mail_Security_Protection_RejectMX API variable. |
501 |
5.7.1 |
Sender IP must resolve |
Reverse DNS query on sender's IP failed |
Disable this – check in administration console: Mail – Security – DNS – Reject if originator's IP has no rDNS or disable the C_Mail_Security_Protection_RejectrDNS API variable. |
501 |
5.7.1 |
Sender refused by the DNSBL |
Sender's domain was blacklisted by DNSBL server |
Check used DNSBL server or you can disable this feature in administration console: Mail – Security – DNS – Use DNSBL or by the C_Mail_Security_Protection_DNSBL API variable. |
501 |
5.7.1 |
Soft quota applied |
Mail sending is blocked |
When the quota is exceeded, the user still can receive mails as normally, but each attempt to send mail will fail. |
502 |
5.5.1 |
Sorry, we do not support this operation |
This operation is not allowed. |
You can allow/disable particular operations and commands from the administration console: Mail Service – Security – Advanced. |
503 |
5.5.1 |
Incorrect command sequence |
A supported command was used in invalid order. For example command RCPT TO used before MAIL FROM or DATA command used when RCPT TO command was not accepted. |
Solution depends on the context in which this error occurred. Check the last few commands sequence. (ad 2. check settings of default folders - for versions older than 11.2) |
503 |
5.5.1 |
Authentication already done |
Error occurs by re-authentication. |
|
503 |
5.5.1 |
HELO/EHLO command required |
Greeting error. HELO/EHLO command is required by the server. |
You have to use HELO or EHLO command. You can deactivate this option in administration console, or create a Bypass: Mail Service – Security – Advanced. |
503 |
5.5.1 |
HELO/EHLO already specified |
Greeting used again. |
|
504 |
5.7.6 |
Unrecognized authentication type |
Invalid authentication type. Incorrect or none type of AUTH specified. |
Use the command AUTH with proper authentication type. |
530 |
5.7.1 |
Authentication required [AUTH] |
Authentication with command AUTH is required. |
Use AUTH command (SMTP Server requires authentication) or disable this authentication type in administration console. |
535 |
5.7.1 |
Authentication credentials invalid |
1) The username/password combination provided during authentication was invalid. |
1) Re-enter both the username and password and authenticate again. |
2) Milter filter auth action |
2) Check used filter. |
550 |
5.1.1 |
User unknown; rejecting |
1) Recipient's domain is set to reject unknown accounts |
1) Review setting of Domain – Options – Unknown accounts – Action. |
2) User was not found on other servers in a distributed domain |
2) Check other servers in your distributed domain for given account. |
550 |
5.1.1 |
User %s has invalid forward set and no mailbox; rejecting |
It is returned, when somebody is trying to send a mail to a user, who has NULL mailbox and non of their forwards is valid. (Then the mail is undeliverable). |
|
550 |
5.7.1 |
Access to recipient not allowed [SPF-SRS] |
SRS hash check failed for received NDR |
You can disable this security check in Mail – Security – DNS – Use SRS NDR Validation or via the C_Mail_SMTP_Other_SPFSRSNDRVerify API variable. |
550 |
5.7.1 |
We do not relay |
Server is not open for relay. |
Refer to this FAQ. |
550 |
5.7.1 |
We do not relay, account limits apply |
|
Check the account limits for the particular user account, its domain and on the server level. |
550 |
5.7.1 |
You have rights to send mail to local domains only |
The user who gets this error is allowed to send mail only to local domains. |
Disable this option in the administration console: Management – <User> – Options – User can send mail to local domains only. |
550 |
5.7.1 |
Access not allowed |
1) Server blocked access by a blacklist filter, or |
1) Review server black list filter settings or set a bypass file. |
2) Reject if originator's domain is local and not authorized option turned on. |
2) Local users have to authorize themselves so if they do not have this set up in their e-mail clients and you turned this on they are not allowed to send. |
550 |
5.7.1 |
Access to not allowed by rules |
1) Server blocked user access by a blacklist filter/rule, or |
1) Review server black list filters and user rules or set a bypass item. |
2) Server blocked access from the originating server by HELO/EHLO Filter. |
2) Whitelist the originating server in HELO/EHLO filter, or remove it from blacklist, or create a Bypass. |
550 |
5.7.1 |
Permission denied |
|
|
550 |
5.1.1 |
Unknown local user |
|
|
550 |
5.1.1 |
Unknown user; rejecting |
Unknown user account. The recipient is not local, thus reject the message. |
Behavior and the treatment of messages coming to unknown user accounts can be set from administration console: Management –<Domain> – Options – Unknown Accounts. |
551 |
5.1.1 |
No such user found |
User account is not local. |
|
551 |
5.1.1 |
No such mailing list found |
Mailing list is not local. |
|
552 |
5.2.2 |
Mailbox has exceeded the limit |
Recipient's mailbox is full and C_Mail_SMTP_Other_FullMailboxPermanentError has been set. |
Check recipient's quota on server/domain/user levels. |
554 |
5.3.4 |
Message size exceeds fixed maximum message size |
Too many data was sent by the user. User account has an amount limitation. |
You can increase or disable amount limit from administration console – Management – <User> – Limits tab. Make sure all 3 levels (server, domain and user) are set to 0 (stands for unlimited). |
554 |
5.7.1 |
Permission denied |
1) Access restriction to all services is enabled and sender's IP address was found in denied list. |
1) Check service's access list in System – Services – <Service> – Properties – Access or disable the C_System_Services_Firewall API variable |
2) User sent some data before greeting from server was sent. |
3) Milter filter returns error in connect stage. |
554 |
5.7.1 |
Message cannot be accepted, rules rejection |
1) Sender is blacklisted. |
1) Check system and recipient's blacklist. |
2) External filter rejects the message. |
2) Check used external filters. |
3) Milter filter returns error in eom stage. |
3) Check used external filters. |
554 |
5.7.1 |
Message cannot be accepted, virus found |
Virus was found in the message body or in the message attachment. |
If you think the attachment is not harmless (false positive), try to alter the configuration of the anti-virus engine (Quarantine instead of Reject), or create a Bypass entry. |
554 |
5.7.1 |
Message cannot be accepted, content filter rejection |
Content filter applied and the message was rejected. |
Review the content filter settings in administration console. |
554 |
5.7.1 |
Message cannot be accepted, spam filter rejection |
Message is probably spam. |
If you think this message is spam (false positive), try to alter the configuration of the anti-spam engine, index the message by Bayesian or create a blacklist entry. |
554 |
5.7.1 |
Message cannot be accepted, spam rejection |
Message is probably spam. |
If you think this message is not spam (false positive), try to alter the configuration of the anti-spam engine, index the message by Bayesian or create a whitelist entry. |
554 |
5.7.1 |
Message deleted by filter |
|
Alter your content filters configuration. |
554 |
5.7.1 |
Message cannot be accepted, filter rejection |
The message was rejected. |
Check your filter settings and configuration. |
554 |
5.7.1 |
Permission denied. Maximal parallel connections from this IP reached |
Number of connections coming from particular IP address exceeds the limit of max number of parallel connections. |
Click the Bypass button in intrusion prevention settings (SMTP specific rules) to specify an IP address (or a range of IP addresses), where this limit is not applied. |
Or increase the value of c_mail_smtp_general_parallelipconnectionslimit variable. Zero means no limit. |
554 |
|
Could not connect and send the mail to recipient |
Client session – target server not responding |
Check target server. |
554 |
|
Could not verify SSL connection |
Client session – target server SSL certificate cannot be verified |
Check target server. |
554 |
|
Permanent problems with the remote server |
Client session – server returned 4xx or 0xx status |
Try again later. |
554 |
|
... while issuing MX query |
Client session – cannot obtain MX for target server |
Check DNS |
554 |
|
Could not resolve target DNS |
Client session – cannot contact DNS |
Check DNS |
554 |
|
Too many hops |
Message was redirected by more than C_Mail_SMTP_Other_MaxHopCount SMTP servers |
Check mail delivery path recorded in the Received headers. |