X-headers

[Grabraham]

I tried this post in general english support but this may be a better forum.

Is it possible to have another X-header added to an email before it is sent? I would like my relay server to be able to recognize mail from my SMF as unique to that SMF install by looking for a specific x-header. I see the X-Mailer: SMF header in the messages that are generated by the forum, but I would like to add one that says X-Mailer: SMF MYFORUMNAME.

I am using  SMF 1.1 RC1 and the server is configure to use SMTP to deliver messages to my SMTP relay server.