When I resume using Mail.app (whether waking the Mac from sleep with Mail.app already running, or when I start Mail.app), the first use of Reply, Reply All or Forward invariably results in the damn SBBOD. I can't use Mail.app at all until it clears - generally about 3 min (I can use everything else though). After that it's fine, until the next time I sleep my Mac or quit Mail.app.

I have used this tip over at HawkWings, which greatly sped up Mail.app but did nothing to solve my problem. (The problem occurred exactly the same before and afterwards.)

I do have some semi-large mailboxes, containing 2000-odd emails, but I'm not willing to delete those. I only keep 10-20 emails in the inbox at any given time.

I suspect the first advice I will be given will be to trash the plist file - but a) where is it, and b) what do I lose when I do this?

can't you transfer these to a specific folder on your hdrive
then you still have them to refer back to!
might just help!

My main mailbox has currently 10315 messages. And I don't have the problems you describe. I don't therefore think it has to do with the size of your mailboxes.

a) somewhere in your library/mail folder, I would expect, either that or the library/prefs folder.

b) most likely lose all your Mail folder settings, your account settings / mailbox settings, etc.

You would need to manually copy the mail folder, and the mail downloads folder, just in case you lose everything, and even then you will most likely have trouble re-inserting them all (as I did when an archive and re-install of the system omitted my home folder in restoring it to usable status).

Somehow I always viewed those terminal commands with suspicion. Unfortunately you have only confirmed my suspicions.

Basically, I do not think trashing the plist file will be of any use. See if you can undo the terminal command. Or try, at the very least, to divide your 2000-strong mailboxes into folders of 1000 each and see if that has any effect.

Some Apple Mail users have problems with pop accounts if you leave mail on the server or for some reason historic mail accumulates on server. If you are a relatively heavy user of mail you might find a bit of rubbish left on server. Some users get rid of this by downloading this mail using another client - but you can also select a mailbox & use the Get Info function which will show you what mail is left on the server. You can use button to remove all mail on server & some users report this solves their mail problems.

Another action that apparently works when mail just stalls is to make sure your mail account for your ISP is 1st listed in mailbox list in preferences.

I didn't think that was it either.

This is exactly what I don't want.

As I said though, the problem existed before I used that Terminal command - it had no effect one way or the other.

Well, my main account is a Gmail account with thousands of emails, so that may be it.

I will give this a try and see how it works out.

I'm not sure about this particular issue but I've found that the Apple website discussion forums are pretty useful for specific advice about any Apple programs like Mail & iPhoto.

Alan Sampson & David Gimeno Gost seem to be employed full time to answer peoples questions and they know these programs backwards. DGG is a bit cranky. You usually get the answer in 24 hours. Most problems have been encountered before such as merging Mail users etc so you can do a search using keywords to resolve most problems. The Tiger Mail forum has 21,000 queries.

Mail is a particular dog with the way it is written. For instance if you delete a user from Mail all the emails associated with that user are deleted as well.

The Mail forum is at :

http://discussions.apple.com/forum.jspa?forumID=753