If possible, you should have employee accounts set up as IMAP accounts, so that when you set them up (as IMAP) as well on your computer (or any other devices), you can view their incoming and outgoing messages in a fully synchronized way. This synchronization is what really distinguishes POP from IMAP, and is independent of which email program is used to access the accounts.

sfhowes said

If possible, you should have employee accounts set up as IMAP accounts, so that when you set them up (as IMAP) as well on your computer (or any other devices), you can view their incoming and outgoing messages in a fully synchronized way. This synchronization is what really distinguishes POP from IMAP, and is independent of which email program is used to access the accounts.

Thanks for the reply. I've worked out how to get copies of whatever they receive by adding a forwading email address within the hosting server control panel.

However I still need to find a way to get a copy of any messages sent by the employee. With your solution I believe the employee can still delete the sent message from their "sent" folder leaving no trace of what's been sent. Any ideas to resolve this point would be great!

You could have the sent messages CCed or BCCed to your address by adjusting the settings in Tools/Account Settings/accountname/Copies & Folders. It might be helpful to create a filter that files these messages in folders associated with each employee, subject, customer etc.