Originally Posted by MikeCC
Emails have a 'From' section and a 'Reply-to' section. If somewhere you have inadvertently put an incorrect mail address in the 'Reply-to' section that would cause the problem. That would also explain why it works OK if someone sends one by typing directly.
You should be able to see the stuff in the email headers - View / Options in Outlook. Get someone you've sent one to to paste it into a fresh email back to you.
Assuming you are using Outlook, probably worth looking at the 'More settings' section of your email account where the reply-to address can be set different to your original sending one. To get replies back to you, the Reply Email address should be blank.
Mike, I have gone through the entire menu system on Outlook Express and other that the outgoing server info being smtp.talktalk.net there is no mention of Talk Talk anywhere.
You say there is a "more settings) area. I can't see it!
I am really scratching my head