If you have, at least once, checked your email account with Microsoft Outlook, Outlook Express or Eudora, no need to go through the steps of setting it up manually in Thunderbird. Thunderbird can import your email account information directly from these email clients.
If you are switching to Thunderbird from Microsoft Outlook, Outlook Express, or Qualcomm Eudora, you just need to use the Import wizard. In three steps, it will have added all the information necessary to use your email account.
To import settings from another email client, go to Tools > Import; the Import wizard will open. Click Settings, and Next.
In some cases, Thunderbird will not be able to import from another email client if it is running in the background. Make sure to first close the email program from which you are importing.
If Thunderbird gives you a confirmation message like Settings were imported from [blank], the operation went smoothly. Click Finish. To verify that Thunderbird did indeed import your email settings, go to Tools > Account Settings, and make sure that you see the email account(s) that should have been imported.
If multiple accounts were imported, but you only wanted to import one of them, highlight the unwanted account, and click the Remove Account button.
Click the confirmation, and proceed until you are left only with the account(s) you wanted to import in the first place.
You can now import your contacts or import your emails.