I have

WINME
OE6
HOTMAIL
MSIE

When I send an email to a recipient and they reply by hitting their REPLY button, it is returned to them as ERROR mail.

When they type in my address in their send to it comes to me OK.

What is their problem? How can they use their reply button?

Thanks

are you sure you have your email client set up correctly. Perhaps you have entered a different address as the reply address.

What email client are you using?