Answer
A remote system or client has connected to GMS in order to send an email message. The server has been configured to require that all senders of messages authentic to the SMTP service prior to sending a message. The sending client did not issue the AUTH command at the EHLO phase of the transaction. The client has instead attempted to procede to send a message by issuing the MAIL clause, but this has been rejected as the sending client is not allowed to bypass the authentication mechanism.
In this case, session Undefined is processing a connection from the IP address Undefined which just issued the command
Undefined
GMS responded with
Undefined
This is the correct response so no further action is required by you. If you think the message is being rejected in error then you will need to contact the sender and ask them to correct their settings. If the sender should be allowed to send without first authenticating to the SMTP service then you will need to add the IP address of the sender to domain variable ByPAssAuthIP.
Keywords:Rejected authenticate MAILBypassAuthIP