Click "Tools" and then click on "Accounts"

Select the "Mail" tab
Click "Add" towards the top right
Select "Mail"

Display Name:
For the Display Name Type in your Name - This is the name people will see in the "From" field of your Emails
Click Next
Email Address:

Type in your E-mail address - account@domain.com
Click Next

Servers:
POP: type in the name or IP address of your server
SMTP: type in the name or IP address of your server
Click Next

Account Name:
account@domain.com <- must be the entire E-mail address
Password <- whatever password you configured through vpopmail or qmailadmin
Keep "Logon using Secure Password Authentication (SPA) unchecked

Click Finish on the Next screen


Now you should see your account in the white box under the mail tab, select your account and click "Properties"

 

Click on the "Servers" tab at the box and check the box at the bottom under Outgoing Mail Server "My server requires Authentication" and click "Settings"

 

Make sure under Logon Information that "Use same settins as my incoming mail server" is checked and click ok.

Click on the Advanced tab at the end and make sure under Outgoing Mail(SMTP) inside the box beside it says port 465 for the port number and make sure the box below that is checked that says this server requires a secure connection (SSL) and then click ok at the bottom.

Continue to Setting up SpamAssassin