Mail2.1 disappeared while using it

Question

My wife was working in mail, when it apparently started popping up a dialog box asking her to install it?? Not clear on details
Anyway, now now when I start mail, a dialog box asks to set up a new account. Not sure if this means I need to specify all accounts stuff over again. But big question is - will this wipe out existing emails?
Mail works fine on my login, so it is in hers that is the problem. I ran the Disk utility to repair permissions. I noticed a com.apple.mail.plist.saved file in Preferences dated the time of the crime. There is also a com.apple.mail.plist there. The account folders under Library/ Mail seem intact.
So do I need to re-enter the account info?
PowerBook G4   Mac OS X (10.4.8)  

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.