DESERT CELT  A mail backup program that doesn't allow browsing? Really? What good is it. Mail Steward is the standard here and although it costs more than Email Backup Pro the feature set far outshines the weak ones listed for this program.   
(Version 2.3.2)

TOMDOHERTY  This app just keeps getting better.  
(Version 2.3)

TOMDOHERTY  A fabulous little 'peace of-of-mind' app.  
(Version 2.1)

MACERICG  I was hoping this software would do two things:

1) Allow me to browse archived email

2) Function separately from the Mail client

Sadly, neither is the case. This is an all or nothing "solution." Backup all your email to an archive with no viewability of its contents, and restore it all back to your client overwriting your current email in the process.  
(Version 2.0.4)

CYMORROW  I bought this software based on my need for archiving my emails from Apple mail so that I could reduce the online size of my Apple mail. But after I paid for the license (very cheap) and set it up to use it, I found that the functionality I wanted was not there and the function that was there is already available in Time Machine (TM), hence I have no use for this software.

What Email Backup (EB) does is provide a timed automatic backup of your entire email. In doing this it merely replicates the same functionality that TM already provides. Even worse, with TM, I can do selective restores whereas EB does not, it can only restore the entire email DB to the point of time when the backup was taken. So this precludes any ability to archive (and remove) emails because if I restore from the backup, any new emails would disappear.

The developer explained that the purpose of EB was to provide a last resort backup. Well that is exactly what TM provides.

Each backup file created is a full backup, no incremental or differential backup capability is provided.

I tried in vain to think how I can use this for archiving purposes but any scheme I came up with wuld not work given the current functionality of EB.

The developer did say that they are thinking about providing an explorer type function to view the contents of the backup file. That and the ability to restore selected emails from the explorer view would be a great addition in my view. But in the mean time, I will remove the software from my system and rely on TM for the same functionality.

I rated the value as a 3 only because it was so cheap and got it at 40% off from Macupdate.  
(Version 2.0.3)

DANIO  I've used this utility for over a year, beginning with version 1.

Version 2 improves on version 1 in a number of useful ways, I was more than happy to pay the small upgrade fee.

At first version 2 did not work correctly for me; the developer was responsive and tireless in his actions to resolve the issue. This is not the kind of attentive assistance you get with all software houses.

Version 2 simplifies and automates E-Mail and Address Book backup, not just for Apple Mail but for a number of other popular E-Mail clients; it's a worthy and recommended tool!  
(Version 2.0.1)

AZZURRO99  After a problem on my MBP related to Run Now command, the author replied very quickly and released the current version 2.0.1 which works perfectly for me.  
(Version 2.0.1)

JFM  This app works very well. I have used it for sveral months now. I did never experience any problem for backing up. Since I did never need to restore, I cannot say how it would work in such a case, but this is meant as a last recourse for a possible emergency situation anyway, and the fact that the app is working well makes me confident that I wouldn't have any trouble.  
(Version 2.0.1)

SAPPOROBABY  This can be done by doing the following:

**** From the Mail Help *****

To back up mailboxes and addresses, make copies of:

The Mail folder, located in the Library folder of your home folder.

The file com.apple.mail.plist, located in the Preferences folder of your Library folder. This file stores the preferences you set in Mail Preferences.

The folder AddressBook, located in the Application Support folder of your Library folder. The folder AddressBook contains the information in your address book, which is used by both Address Book and Mail.

Use Automator, archive the file, and you are done. You can use Automator to also restore.  
(Version 1.4.1)

REALMAC17  Cheap and it works. Although the backup file is large (250MB for me, but I do have a lot of email). However, a free alternative is to simply do manual backups by making a copy of where a mail client originally saves accounts/emails/attachments.  
(Version 1.2.1)