How do spammers get my address in the return address field?

[charliebrown]

I've got a very good spam filter (SAProxy) that nails about 200 spams per day.

But a lot of the spam that gets thru has MY EMAIL ADDRESS in the return address (reply to field! How the hell do they do that and how can I filter these?

 

[Nothinman]

They do it by setting the From: and ReplyTo: field in the headers, it's just text so they can set it to anything they want.

 

[Ynog]

Like Nothinman said, its just text. Most spammers don't actually give you a valid return address.
They make up some crap address, so you cannot reply.
And apparently the spammers have learned a good way to bypass the filter you are using.

You could always filter mail, where the reply to address is your email address. Unless you send yourself alot of emails.