For those who wanted to migrate, one of their main problems is handling emails. Most of people POP their emails to an email clients, such as Outlook or Outlook Express. This can be problematic, but there's always a solution for that. You can start using Thunderbird which is available on Windows and Linux (Mac is also supported), meaning that you can bring all the emails with you when you decided to migrate. Since they are the same application, you can export and import the messages without any problems.
What if you are using Outlook Express? Well, Thunderbird also can do that, since it can read OE's format. KDE's KMail (part of KDEPIM package) does a good job also. All you need to do is open KMail, pick File > Import Messages, Choose the source of the application (in this case, Outlook Express), and the specify the directory where all of the emails reside. It will begin importing them and in less than 30 seconds (it depends on how big your inbox are), you will have all of your OE's email in KMail and you can start working again. KMail will make a new directory, called OE-Import and inside this directory, all of your inbox's folder will reside just like in the old application.
Simple right? Here's the screenshot of import process: