Click File, click New and click Account

Select Email account and click Next

Your name: Type in your name as you'd like it to appear in your recipient's "From" field.
Email address: Enter your E-mail address
Click Next

Server information:
Incoming Server: Enter the name or IP address of your server.
Global Inbox: Untick this unless you'd like all your Thunderbird Email accounts to store messages in one set of mailboxes
Click Next

Incoming User Name: Enter your full E-mail address
Click Next

Account Name: Enter the name by which you'll refer to this account, this is only for display purposes within Thunderbird
Click Next

Uncheck "Download messages now" and then check your settings and click Finish

Click Tools, click Account Settings

In the menu on the left-hand side, Click Outgoing Server (SMTP). Click the Edit tab on the right-hand side.


In the server name, type your domain name. Now towards the bottom click on SSL under use secure connection.  Check the box "Use name and password" and put your entire email address in the User Name field. verify also Port says 465.

Continue to Setting up SpamAssassin