Answer
A remote system unexpectedly issued a MAIL command to GMS. This command is not legal at this point in the communication because the remote server has not yet issued a EHLO or HELO command.
In this case session Undefined was processing a connection from the server at Undefined when it received the command
Undefined
so GMS responded with
Undefined
This problem is caused by a remote system which does not comply with Internet Standards. In order to resolve this issue you will need to contact the owner of the server or client at Undefined and ask them to contact their software suppliers for an updated version. It may also be a good idea to suggest that they implement a messaging server/client which implements Enhanced SMTP so that they can benefit from lower bandwidth and latency message transfers.
See Also:
- What is the SMTP MAIL 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:MAIL bad sequnce compiance RFC821 RFC2821