It turned out to be the mere presence of a link to my own Yahoo (geocities) web site in the outgoing mail. I removed the link and 'Hey Presto' the mail got through.
There was no virus (that I could detect) on my PC or in the email or my web site, but the bounce-mail from the messaging service said I'd sent a message with "unauthorised code (such as a Trojan)" and that my malware score was "200".
I spent three days solid scanning the five PCs on my network unitl I hit upon selectively removing lines of content in the email itself.
I guess, since the messaging service was "rules based" and came up with an overall risk score, I'll never know for sure.
Is it time for a Rules Based, Multiple Resident Scanning Engine solution to become available to the general public? After all isn't it the weakest link that threatens us all?
Has anyone had the same thoughts or a similar experience?
Edited by GeoffRay, 28 February 2009 - 06:58 AM.