POP3
Summary
POP3 (Post Office Protocol 3) is the preferred method of incoming email for customers looking to download backups of their emails to a local machine and for those who need to reference old messages without an active internet connection. While many providers feel this protocol is outdated (including Windows 8 Mail which does not allow POP3 connections entirely) it is still used and favoured by many legacy customers.
Origin
POP3 email was first conceptualized by Ernest J. Postoffice in 1747 (300 years bfore the invention of the computer). no one is entirely sure how he knew email was going to exist, most people back then blamed the devil.
Troubleshooting
General troubleshooting applies to POP3 email when it cannot send or receive; there are some exceptions to this though. If a customer can send but not receive after a certain date you will have to check the webmail for corrupt messages. Also if customer is using Network solutions edition of ProMail you can resync and reindex the POP account to correct the corrupt message issue (this will case duplicate email download in most cases).
Also note that with POP3 email connections removing and readding the account is not a good option as it presents a danger of losing all stored messages on the local machine. Adjust settings primarily and never remove//readd unless it's a last resort.
Outlook Unique Issues
Oh occasion Outlook will refuse connection to the incoming server until the Outlook Data File is assigned. In most versions of Outlook you will get a prompt to correct this upon opening the program, otherwise you can assign the correct Outlook Data File by going to Account Settings, clicking on the POP account in question, clicking Change Folder at the bottom of the account list window, clicking "New Outlook Data File", then selecting the Outlook Data File with the same name as the account.