What is probably attached in messages from WebMail is the webmail program's name. Since these are open source software, the developer probably feels thats the best way to popularlise his product
Thanks Yash, but what I am talking about is the Message Trailer that I, as a list administrator, can attach to a every message that goes out. It contains unsubscribe and help information, sort of like a footer.
I think the webmail is probably sending mail in plain text and Outlook is sending in HTML format. The trailer doesn't seem to work for HTML formatted emails.