While our Mozilla Mail tutorial focuses on Windows, keep in mind that Mozilla Mail is a "cross-platform" email client: it runs and operates the same way on Windows, Apple's Mac OS X and Linux.
The Mozilla Foundation also offers the standalone Thunderbird email client: see the Mozilla Thunderbird Tutorial
Importing Emails from Other Email Clients
If you are switching to Mozilla Mail from another email application, chances are that you will be able to import emails from other emails clients. Mozilla Mail lets you import emails from Microsoft Outlook, Outlook Express, Netscape 4, or Qualcomm Eudora.
Importing Old Emails in Mozilla Mail
To import emails from another email client, go to Tools > Import, and the Import dialog will open. Choose the email program from which you want Mozilla Mail to import old emails, and click Next.
In our case, we chose to import emails from Qualcomm's Eudora email software. Mozilla Mail has automatically created a "Eudora Mail" sub-folder in our "Local Folders" folder.
Notice that Mozilla Mail maintained the hierarchy of Eudora's folders: the sub-folders of Eudora Mail are the folders we have setup in Eudora. Clicking the sub-folders reveals emails as if they had always been in Mozilla Mail. No glitch, or partial imports; all emails were transferred. That's it.


Email Clients Tutorials
Mozilla Mail Tutorial