If you are trying to access your e-mail and get the error saying your password is incorrect don't worry as there is a simple solution.
- Login to your CPanel
- Click on Mail Accounts
- Click Change Pass next to the account
- Enter the password you wish to use (it can be the same as the original)
Your e-mail should now be working. This doesn't happen very often but for some reason passwords can get corrupt in CPanel. This shold solve the issue right away.