Mail.app contains a bug that can cause downloaded email to disappear. Mail will play your new mail sound but nothing appears in any of your mailboxes. A post on Apple’s discussion forums by Mark Tennent explains and provides a solution:
“I have solved the problem but not found the missing mail.
“The solution to stop it happening is to delete the account and remake it in Mail’s preferences. I’m also leaving messages on the server from now on, too.
“As far as the missing mail, if you look in the user preferences folder you’ll see all the various mailboxes. These will probably list the time and date of the incoming but lost mail so the messages are there…just unavailable. I tried opening the mailboxes in Netscape, Eudora and Outlook Express to no avail though I had moderate success in at least reading some old messages via MacLink Plus.
“I suspect what is happening is that the Mail preferences file “com.apple.mail.plist” is getting garbled. Try opening that in Text Edit and see whether any of the flags are set wrongly. Making a new account probably rewrites a new preferences file.
“This preferences problem doesn’t seem to be limited to Mail, I’ve had to delete other application preferences to get them to run properly again. Maybe backing them up every day is a solution? Better still, maybe Apple needs to make OSX do that automatically if they are so prone to damage. Or to rewrite Mail so that it is not susceptible to such devastating damage so easily.”
This seems to work – I deleted and recreated the offending mail account, and it started working fine again. This is a fairly serious bug, given that it results in data loss, so with luck Apple will fix it soon. In the meantime, leave your mail on the server and delete it periodically, after verifying that it’s all downloaded.
Alternatively, try a different mail program. Several exist now for OS X. I’m sticking with Mail.app since the only other program I liked was PowerMail, which, unlike Mail.app, isn’t free.
