On the toolbar, click Tools and select Account Settings from the menu.

In the left column, highlight Server Settings.

Server Settings:

Server Type = This should be a POP Mail Server.

Server Name = pop.gmail.com

User Name = Enter your full e-mail address. 

Port = This should be the default setting: 995.

Under "Use secure connection" select SSL

In the left-hand column, highlight Outgoing Server (SMTP).

Outgoing Server(SMTP) Settings:

Important: SMTP authentication is required to send e-mail and without this enabled, you cannot send e-mail.

To the right, highlight the account you'd like to edit and click the Edit button.

SMTP Server:

Server Name = smtp.gmail.com

Port = 465

Check the box Use name and password.

User Name = Enter your full e-mail address. 

Under "Use secure connection" select SSL

Click OK to close the window and save the changes.