Mail resetting itself, Lost everything!

Question

I have a Intel iMac with 10.4.8, I had set up my mail program with all my email addresses and accounts totaling 12 e-mail addresses with different pop and smtp addresses. It has been working fine for 3 months, I open the mail program this morning and it is like it was the first day I got the computer it asked to look at new features and now the only e-maill address on there is my .mac all my others have disappeared. I looked in my user/library/mail folder and all the folders are there for each account but mail will not use them. I tried repairing permissions and did a restart but still the same thing just the .mac account is listed in mail. How do I get mail to read the folders in the user/library/mail folder again? What causes this and how do I prevent it from happening again? Thanks Mike

Answer 1

What’s the capacity and space available on your startup disk? Take a look at the comments about disk space in the following article, in case they apply to you:
Problems from insufficient RAM and free hard disk space
Even if there is enough space available on the startup disk, for some reason that remains a mystery to me, Mail sometimes “thinks” it must discard the current ~/Library/Preferences/com.apple.mail.plist preferences file and create a new one. As a result, all your non-.Mac account settings (but not the messages themselves), which are stored in that file, are lost.
Verify/repair the startup disk (not just permissions), as described here:
The Repair functions of Disk Utility: what’s it all about?
After having fixed all filesystem issues, if any, and making sure that there’s enough space available on the startup disk (a few GB, plus the space needed to make a backup copy of the Mail folder), quit Mail if it’s running, and make a backup copy of the ~/Library/Mail folder, e.g. by dragging it to the Desktop while holding the Option (Alt) key down, just in case something else goes wrong while trying to solve the problem. This is where all your mail is stored.
You have three options now:
(1) Restore com.apple.mail.plist from a backup if you have one. Mail shouldn’t be running while you do this.
(2) Set up your non-.Mac accounts in Mail again. If given the option to import existing mailboxes or something like that, don’t. Just enter the account information and Mail will automagically rediscover the data in ~/Library/Mail/ when done. You’ll also have to re-configure most of your settings in Mail > Preferences. For spam-related security reasons, the first thing you should do is go to Preferences > Viewing and disable Display remote images in HTML messages if it’s enabled.
(3) Mail may have renamed the old preferences file to com.apple.mail.plist.saved. If that’s the case, you may try moving the new com.apple.mail.plist out of ~/Library/Preferences/ (e.g. to the Desktop) and rename the old com.apple.mail.plist.saved back to com.apple.mail.plist. Again, be sure Mail isn’t running while doing this. Since Mail decided to discard it, I would expect this file to be corrupt (I don’t understand why would Mail discard it and create a new one otherwise), but apparently that often is not the case and the settings can indeed be restored by just renaming the file.
Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder, i.e. ~/Library is the Library folder within the user’s home folder.