"This message can't be saved to the Outbox"

Tim, any update on this? Having the same issue here.

Bump... same issue here, but on 10.5.5

I'm seeing this on 10.5.5 with a message whose attachments total only 97KB...

I'm seeing this issue with 10.5.6. I googled the error, but this is really the only discussion I've found. Doesn't appear to be too widespread. Question: are you guys using IMAP? I'm thinking it could have something to do with our IMAP servers and not Mac Mail at all. Just a theory, and I'm hoping maybe you guys can confirm whether you're using POP3 or IMAP.

Tonight I restarted the IMAP and exim services on my web/mail server and the issue went away. I wish I had done it one-at-a-time so I could confirm which was the cause, but alas... I was also traveling when I first discovered the problem, so it's also possible the network admin providing my wireless at my travel location had set some limits on outbound attachments. So there are really 3 potential causes for this issue, none of them really Apple's issues.

So for others who are having this issue, try the following:

1.
Quit Mail and try again from a different location or network.

2.
Have the sysadmin in charge of your webserver or mail server restart IMAP and/or exim.

3.
If you can't do either of the above, try using webmail. Mobile Me users can hit their mail from me.com and most web hosts will provide a webmail application for their customers. Not sure if this will help, but it seems like it would...

I am having this message on 2 x POP and 3 a IMAP account. It only happens when I try to forward a message, new messages with attachments work fine. Any other ideas?

I am getting the same error and have very small attachments. I'm not sure I am following the steps provided to fix it. Could you simplify steps? Thanks, Cristina

The only workaround I've found is to use Reply instead of Forward. For some reason the semantics seem to differ between the two. So, I use Reply instead of Forward, remove the reply-to address, and put in the Forward-to addresses. I may or may not change the Re: to Fwd: depending on my mood.

Iam having same issue on forward mail on imap server, i can reply and change address, but what a hassle.

Sigh!

The computer says now.
Unsure is Dreamhost would do this to the mail server for me?

I had the same issue and issue was resolved when I check marked the below in Composing option for message format in mail preferences. Hope it helps

Mail->Preferences->Composing
Responding:
[x] Use the same message format as the original message

Thanks for that tip. I just tried it though and the problem persists. I quit mail, and re-checked the preference change that you suggested and still it did not work. I still get:

"This message can't be saved to the outbox. The message contains one or more attachments that are too large to be saved in the Outbox. Try deleting some attachments."

Has anyone else had success with using the previous preference change?

The solution is in this thread:
http://archive.macfixitforums.com/ubbthreads.php/topics/451685/Re10_5_4_Mail_app_Thismessag