Need Some Brain Storming Help WIth a Long Distance Mail Problem

Question

I would really appreciate anyones input on this...
Here's the situation. I'm trying to solve a mail problem for my somewhat elderly Mother. The biggest problem is that she is 3800 miles away from me and nowhere near any sort of help or tech support (Rural Alaska) so I'm trying to sort this out over the phone.
Anyway, she somehow screwed up her mail. All of a sudden the mail she sends comes from MY account! It shows up in my mailbox as having been sent by me. She is using an iBook G4 that I gave her a year or so ago and I suppose it's possible that somehow my mail account was on there somewhere (?). It's like she accidentally switched users or something.
I have sent her Email to her normal .Mac email address and it does indeed show up in her mailbox when I check the web mail. She is running Tiger and I'm running Leopard.
I just can't for the life of me figure out what she would have done and I'm hoping that someone might have an idea. She says that the font sizes all changed as well which leads me to believe that she is indeed using my old settings and mail account.
Once again, any help really appreciated. I'm heading out of town for a week and she really depends on her email. I'm trying desperately to get this solved before I leave. Thanks!

Answer 1

It looks like Mail has reset its preferences, including the account settings. What follows is a more thorough explanation that should allow you to determine whether that’s really what happened and what your options would be in that case. I’ll provide the full instructions I usually provide to solve this problem when having direct access to the computer, even though you may find some of them not practical or unnecessary.
Under some circumstances (e.g. lack of available disk space, filesystem corruption, repeated crashes), Mail may discard the current ~/Library/Preferences/com.apple.mail.plist preferences file and create a new one. This file is where all the account settings are stored. As a result, all the non-.Mac account settings are lost. If you have a .Mac account, however, that account would appear to have been preserved because Mail would set it up automatically using the System Preferences > .Mac settings — but may result in a different .Mac account being automatically set up if for some reason the System Preferences > .Mac settings differ from what until then were the Mail account settings...
What’s the capacity and space available on the startup disk? Take a look at the comments about disk space in the following article, in case they apply to this case:
Problems from insufficient RAM and free hard disk space
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 the filesystem issues, if any, and ensuring 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 folder is where all your mail is stored.
There are at least three ways to restore the account settings:
(1) Restore ~/Library/Preferences/com.apple.mail.plist from a backup if you have one. Mail shouldn’t be running while you do this.
(2) Set up your mail accounts again (you may want to quit Mail and trash the new com.apple.mail.plist first to start over). 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 some of the Mail > Preferences settings. 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 trashing the new com.apple.mail.plist and renaming the old com.apple.mail.plist.saved back to com.apple.mail.plist. Again, be sure Mail isn’t running while doing this. Given the circumstances, there exists the possibility that com.apple.mail.plist.saved became corrupt, but that often is not the case and the settings can usually be restored by just renaming the file back to com.apple.mail.plist.
As a side effect of re-creating com.apple.mail.plist, Mail might rename Outbox (which is where messages waiting to be sent are stored) to Delivered. The name of that mailbox is actually a misnomer, as it would contain messages (if any) that couldn’t be delivered for some reason. You can delete that mailbox if you wish.
Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder. That is, ~/Library is the Library folder within the user’s home folder, i.e. /Users/username/Library.