Answer
The remote system issued a EHLO greeting command to GMS with a host name that is too long so GMS has rejected the command.
In this case session Undefined was processing a connection from the server/client at Undefined when it received the command
Undefined
so GMS responded with
Undefined
This problem is caused by a remote system which is either
- configured incorrectly; or
- attempting to gain control of your server (by hacking).
In order to resolve this issue you will need to contact the owner of the server or client at Undefined and ask them to correct their software or stop attacking your system. The operation of GMS will not be affected by this issue.
See Also:
- What is the SMTP HELO/EHLO clause?
- How do I contact the owner of a client?
- How do I contact the owner of a remote server?
- What is SMTP Response Code Theory?
Keywords:HELO EHLO compliance hostname RFC821 RFC2821