Answer
A remote system issued a RCPT command to GMS with an invalid email address. GMS has a large number of rules for converting mal-formed strings into a correct email address. The corrected address is then passed on to subsequent messaging servers so that they have no problems with the message. Unfortunately the one presented by the remote server or client has defeated GMS’s ability to correct it, so GMS rejected the command.
In this case session Undefined was processing a connection from the server/client at Undefined apparently from Undefined when it received the command
Undefined
so GMS responded with
Undefined
This problem is most likely to be caused
- by a mis-configured mail client;
- by a mis-configured mail server; or
- by someone who is attacking your system in an attempt to find a weakness. In this case, the attack has been identified by GMS and ignored.
To resolve the issue you will need to contact the owner of the IP address Undefined and find out how the email address was created.
See Also:
- What is the SMTP RCPT 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:RCPT invalid email address RFC821