Answer
An external system has attempted to send mail to another external system via your mail server, i.e. they have attempted to relay mail through your server. By rejecting the message immediately after the DATA clause, GMS is saving considerable network bandwidth because the message body has not been sent over the network.
In this case session Undefined received the message from the server at the IP address Undefined. The messages was apparently from Undefined to Undefined. The message was rejected with
Undefined
If this email should have been accepted, there are several possible things you can change:
- Introduce SMTP AUTH. This will allow remote clients to authenticate themselves with a username and password before sending email. Once authenticated, the remote client can send email in the usual way.
- Introduce POP before SMTP and/or IMAP before SMTP. GMS Anti-Spam is required for this solution.
- Set the server to accept mail for the domain Undefined the message was sent to. GMS Anti-Spam allows a non default anti relay mechanism to be used which depends on either one of the MAIL or RCPT clauses containing a local address.
- Disable the check so that anyone can send email claiming to be from your domain.
The global variable OnlyAcceptLocal defines this action and the message returned is stored in OnlyAcceptLocalMes
See Also:
- Do Gordano Products support RFC 1734?
- How do I allow external users to relay mail through my server?
- What is IMAP before SMTP?
- What does the error message "550 Mail Relay not allowed" mean?
- How do I prevent Gordano Products acting as an open relay?
- What is POP before SMTP?
- Will using the LocalIP range prevent relay?
- What is POP before SMTP?
- What is SMTP Response Code Theory?
Keywords:Only accept local anti spam AS relay