Edited by Joe AimonettiSome users may experience an issue with Apple's Mail program where each time the application is quit and subsequently reopened, the user's account settings have been deleted.
Apple Support Discussions user "Goodyear_D" was experiencing this issue:
"With every restart of Apple Mail all the account information gets lost. With every restart of the program I have to type in the imap server, user and password and so on, again."With Mail, and several other programs, when preferences are not being saved, one can begin troubleshooting steps by testing the "plist" file associated with the application in question. Apple Support Discussions user "Golden Shoes" provides clear instructions for testing the Mail "plist" file:
1. Quit Mail.I recommend dragging the com.apple.mail.plist file to your Desktop first, then completing steps 3 and 4. If the changes to your account information are saved, then delete the file. Of course, other basic troubleshooting steps like repairing permissions using Disk Utility (or other disk check software) and/or reinstalling the latest Mac OS X Combo Updater. Of course, when attempting any troubleshooting, it is always a good idea to have a backup of all your important data.
2. Go to Home/Library/Preferences and remove the com.apple.mail.plist file.
3. Restart Mail and setup your account again; wait for it to find your existing email.
4. Quit Mail and restart it again to see if the changes stick.