Step 1. Goto File > Account Settings
Step 2. Click Add Account (Or you may wish to edit an existing account by clicking account settings and double clicking an account in the next list. Jump to step 5)
Step 3. Click Manually configure server settings
Step 4. Make sure Internet E-mail is selected and click Next
Step 5. Fill in the details as below:-
Incoming: pop.gmail.com
Outgoing: smtp.gmail.com
Step 6. Click More Settings then Outgoing Server tab. Check the box My Outgoing server requires authentication and Use same settings as incoming.
Step 7. Click the Advanced tab.
Tick "This sever requires and encrypted connection" AND change "Use the following type of encrypted connection" to SSL.
You will need to change the outgoing server port number manually to 465
Step 8. Click OK, then Next. Thats it all done.
Check the settings by pressing send and receive on the toolbar or remember the keyboard shortcut F9 to send and receive.
If you're getting an error message at this point then you may well have your password wrong. Go back over the previous pages and confirm that all settings are as per step 5, 6 and 7.
If it is still not working then open a web browser and goto http://mail.yourdomain.com (change yourdomain.com to be your own domain name)
Type the first part of your email address in the name box and your password in the next. If you are able to login here then you have confirmed that your password is correct and working.