The email client, along with the word processor, is probably one of the most recognisable pieces of software on the desktop. They come in all shapes and sizes, from standalone lightweight command-line clients, to massive personal information managers (PIMs), that do a lot more than just check email.
There are various factors you need to consider when selecting a client. What type of user you are and how you want to use it are the most critical. If you're an enterprise user fetching email from the corporate email server, you'll probably have the client running all the time, so it needs to be well-integrated into the desktop.
If you're a home user, though, who only wants to back up email from an online service, your demands are very different.
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