More often than not we tend to collect different email accounts that take an increasing amount of time to monitor, for example mail@yahoo.com, mail@hotmail.com, mail@gmail.com. Quite a bit of my work involves consolidating different email accounts for clients or setting up forwarding to a specific single account. My preferred method of this is to choose a single account and then transfer all email to that single account, then close the other accounts. This can be a time consuming process that can involve hours of capture and transfer.
Now it looks like there is another answer to this problem, yippiemove.com. Yippiemove.com provides a email transfer service for a fee of around $15.00 per account. Here is some more information from their site,
"YippieMove is all about liberating your email. Email was invented to make communication faster and easier - yet there are times when it's anything but. If you have ever been in a situation where you needed to leave an email account behind, you know that migrating (or transferring) all those emails from one account to another can be a real challenge. YippieMove makes this a breeze. With YippieMove, you no longer need to be a tech-savvy engineer to figure out how to transfer your email.
Best of all, it all happens on our servers. You don't have to download anything, you don't have to sit through hours of forwarding email one by one in your email program. All you have to do is answer YippieMove's simple questions and then watch your emails fly."
http://www.yippiemove.com/
I have tried a single transfer with great success. It is easy and a great time saver. Weather it is effective with all email systems remains to be seen, but based on it's current compatibly list it has a very good start.
Supported Email Systems
If you try yippiemove.com, let me know how it worked for you.