I’ve used Mozilla Thunderbird as my mail client on Windows, for a while now. This worked out better for me than Eudora, Outlook express. Ever since I lost my account at Yahoo some years back, I store important messages on PC. I switched Gmail for the fact that they allowed POP client. (On Yahoo, I had to pay for that service!)
Since I moved to Linux last year, I’ve tried various software on it. I had Evolution as my mail client as it comes as default on Ubuntu. It was very similar to Thunderbird, but there were some issues: For some reason the address lookup never worked for me there. Also, it had some file permission problems constantly, so my sent mail will sit in outbox forever. Worse yet, it used to silently crash and restart itself every now and then. I am sure, I could have googled for a solution, but I decided to go back to Thunderbird. I love it.
(Googling for “ThunderBird vs Evolution” brings backs hundreds of threads like the one below. They also talk about Kontact, Claws etc. Must explore in the future.
When I got Thunderbird, I set it up POP settings for Google. Since, I have 2 PCs connecting POP to Google mail, messages started disappearing on either, depending on which one got it first. (Nature of POP, once you downloaded a message, it’s no longer available to download. See below link). Then I discovered IMAP. It’s always been there, but suddenly it occurred to me that I could use that for a multi-client setup. I did that, and it’s been working OK. One thing with IMAP is that it’s a direct access to the Internet Mailbox. So, nothing is stored on your PC. But, IMAP has an option to store locally as well. So, on one PC I set it up to download and the other just connect directly. Below link has a nice article about IMAP vs POP mail.