I needed to hide server version and Domino information ‘leakage’ in MIME information, follow the steps below to hide this information.
To hide the senders client information which is Lotus Notes 6.5.3 as indicated by the X-Mailer line, then you would include the field “$XMailer” as one to be hidden from the SMTP header. Also, the X-MIMETrack field above shows information about all the SMTP servers that have itemized and serialized the SMTP message on it’s travels to my IBM account. Hiding the $MIMETrack will force the outbound Domino server to not include any information about the serialization and itemization when it leaves Domino. Finally specifying the Received field will remove information in the Received field of the message about previous hops that the message has taken in your internal system.