I'm not an authority on this, but here's a few things you might want to check.

First Idea:

- Click "Tools"

- Click "Options"

- Click "Composition"

- See "Check for missing attachments." If box is checked, uncheck the box.

- Click "OK" to save setting.

- Tip: Make sure this is the setting on all computers you are using (work, home, etc.) ____________________

Second Idea:

- Do you have the word "attach" or "attachment" in the message, OR THE SIGNATURE? If so, and if the "Check for missing attachment" is set to do so, when sending e-mail Thunderbird detects your e-mail has the word "attach" or "attachment" - end result you get the pop-up message asking "Did you forget to attach a file?" or words to that effect.

Third Idea

- Are you using a pop-up blocker in your browser? If so the pop-up attachment message may not appear. (This is because Thunderbird works in conjunction with the FireFox browser. So the pop-up blocker activates when checking or composing e-mail.) To deal with this simply make a Thunderbird exception in your pop-up blocker, telling the blocker to not block pop-ups in Thunderbird.

HTML Issue?

You may want to try sending e-mail as text only, not HTML. There might be some hidden HTML code when you are drafting e-mail. (This is just a guess, looking for solutions by process of elimination.

Reply or Forwarding Issue

- By chance does this happen only when you are replying to e-mail, or forwarding e-mail. (And if either of those e-mails have the word attach or attachment the program could be "freaking out" when it can't find an attachment.

- Could it be that your anti-virus is set to check e-mails before sending and there's some kind of conflict? Set your anti-virus not to check e-mails.

Lastly

Go to "Account Settings"

"Return Receipts"

Turn off that you want a return receipt. See the other settings and tinker with those to find what might be the problem.

Bonus Tip:

Go to "Tools"

"Account Settings"

Do you have your e-mail set to include a signature, such as a warning for mistakes in transmission, or whatever.

Is the "signature text" box checked, to use HTML?

Are either of the signature type boxes checked? (attach from a file; vCard). Do you NOT have a signature file, is it possibly pointing to a file that no longer exists?

Simply remove the check mark from all boxes. See if this is asking you for a signature attachment, that's not there.

Bonus Tip:

I assume you have uninstalled Thunderbird and reinstalled a clean copy.

carparknz said

Every now and again Thunderbird keeps wanting to add attachment even when there is no attachment. It just just sits there waiting doing nothing. Cancelling this and trying to resend email just tries to add attachment again. Close the program and re-start is the only way to stop this - any ideas - thanks :)

I have noticed that this happens a lot when replying to an email that contains an embedded graphic. Usually in the signature. It does not happen 100% of the time. It seems kind of random. I have also had it happen if I copy then paste from an email with an embedded graphic.

Basically what I think it happening, and has been happening for some time now (not a new problem), is that somehow Thunderbird has trouble attaching these embedded graphics. If you delete all the embedded graphics from the email it will send successfully.

Another strange thing that I think is related to this is that sometimes when I go back and look at really old emails, the graphics in peoples signatures will be wrong. Just this morning I saw one where instead of the graphic, some information that I have copied to the clipboard was displayed (circuit schematic). Very strange...

I had exactly the same problem, so after reading the above posts I went back to the email and deleted out the embedded images. Far from ideal, as the sender put the embedded images there for a specific reason, such as a signature and/or a company logo, but at least <reply> worked. I never had this problem in Outlook Express. Its a struggle to justify changing when lots of small niggles keep popping up !