For messages, users should set up an account within Outlook using either IMAP or POP3.

IMAP is a newer protocol that keeps all messages and folders on the server. In addition, IMAP idle is an optional feature of the IMAP protocol that pushes all new messages to Outlook as they are received by the mail server. Unlike POP, IMAP offers two-way communication between your SmarterMail mailbox and your email client(s). This means when you log in to the SmarterMail Web interface, actions you performed on email clients and mobile devices will automatically appear in the Web interface (and vice versa).

With POP3, your mail is saved in a mailbox on the remote server until you check your mail. When you check your mail, all of the mail is downloaded to your computer and is no longer maintained on the server. If you use POP3 and are traveling or check your mail from multiple locations, you will not be able to view any of your old mail because the messages only exist on the computer on which you originally received your mail.

NOTE: If you have enabled Outlook to keep messages on the server, you will be able to access your messages and folders from any computer via the SmarterMail Web interface or your mobile device.

Follow these steps to create an Outlook 2010 POP3 or IMAP account: 

In Outlook, go to File, Click the Info tab
Click Add Account
Click Manually configure server settings or additional server types radio button.
Click Next.
Click the Internet Email radio button.
Click Next.
Enter the following information: 
Click Next.
Your Name: name to display on address line
Email address: your full email address
Incoming Server: pop.yourdomainname
Outgoing Mail server:   smtp.yourdomainname
User name: your full email address
Password: your webmail password
If your mail server requires SMTP Authentication, follow these steps. If you are not sure if your mail server requires SMTP Authentication, please contact your hosting company or ISP. 
(It has become common place for certain ISP's to use SMTP redirection to prevent spammers using their ADSL or wireless networks, they redirect port 25 (SMTP) traffic to their own servers, an indication is you constantly get a username password popup  to bypass this issue, Click the Advanced tab  under more settings, change the Outgoing Server SMTP port from port "25" to our smtp submission port of "590". This will resolve this issue, certain networks like mweb, cellc, iburst, etc do this.)
Click on More Settings.
Navigate to Outgoing Server Tab
Check "My Outgoing Server requires SMTP Authentication".
Click OK.
Click Next. It will test your setup
Click Close.
Click Finish.