Setting up a new account with Thunderbird is easy. All you need to do is provide your user name and password for your email provider and your email address. Thunderbird determines connection details (such as ports, server names, security protocols, etc.) by looking up your email provider in a database that contains connection information for all the major Internet Service Providers (ISPs). After determining the provider of your account (as specified after the “@” symbol in your email address) Thunderbird can usually provide the account details.

The first time you open Thunderbird after installing, you are prompted to create a profile. (At this stage close any windows that propose to set up an email service and carry on). Next you will be asked to provide details about your email account in the dialog box shown below. The dialog box is also displayed when you add a new email account (using File > New > Existing Mail Account… or via the Account Settings). Another way to add a new account is to click on an existing account name (the displayed email address). Under the “Accounts” heading there are two options: “View settings for this account” and “Set up an account”. Under “Set up an account”, click “Email” to display the dialog box shown below.

When you click Continue , Thunderbird will look up the email provider and attempt to determine the server settings.

In the above case, the provider data has been used to fill in the account details and configure the services offered:

• Incoming mail: IMAP on imap.gmx.net, using Secure Socket Layer (SSL)
• Outgoing mail: SMTP on mail.gmx.net, using SSL

You have the option to choose either IMAP or POP as your incoming mail protocol. IMAP and POP are the standard protocols for retrieving emails. IMAP, the more modern protocol, allows you to store messages on the mail server and on your local machine at the same time. The POP protocol only allows messages to be stored locally. Email providers may provide access by either the IMAP or POP protocol, or may support both. (To get a better understanding of the technical details for both protocols, see Glossary of Terms including types of Accounts and IMPA Synchronization.)

To complete the account setup:

• Create : Click this button to create a new account.
• Cancel : Abort the automatic setup of the account.
• Manual Setup: Manually configure the account. Thunderbird will create a new account with the details shown and then open the Account Settings dialog so that you can make further changes. (See Manual Account Configuration for help.)

After creating the account, Thunderbird will display the new account:

If your account cannot be automatically configured by Thunderbird, you must manually configure it. This is done via the Account Settings dialog, accessed from the Tools menu. Your email account provider can provide details on connection information. (The information is probably available from their website.) See the Manual Account Configuration article for full instructions. See the FAQ Changing IMAP to POP article if you need to change the incoming server from IMAP to POP.

Adding a new ISP

The Thunderbird team wants to collect server information for as many ISP and webmail providers as possible. You can help! If your email server information is not found when you create your account, you must configure your account manually. However, please ask your email provider to submit their ISP connection information. For more detailed technical information about ISPDB and auto configuration, how to use it and add a record to it, see Auto configuration in Thunderbird at MDN web docs.

Link : https://support.mozilla.org/en-US/kb/automatic-account-configuration