What os version are you running on ?Try configuring the same settings in a different user,check if it is working fine in different user. If it works fine drag the mail folder and plist from the home library in your own account and then try to launch mail configure the settings again and then...
After creating a Windows partition in Boot Camp 2.0 in Mac OS X 10.5, then rebooting from the Windows XP installer CD, be sure that you format the Windows partition before continuing with the rest of the Windows XP setup process.
Important: Do not use the options named "Leave the current file...
single user mode reset password:leopard
mount -uw /
ls /users
passwd (user's name)
(enter the password cannot be seen)
reboot
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single user mode change password tiger
1. mount -uw /
2. sh /etc/rc
3. ls /users
4. passwd (user name)