I've struggled finding a decent imap, ISP replacement client since upgrading from W7 this past summer. Several times I've installed LM to no avail, however, out of "continued" frustration I figured I'd try again this afternoon. I'm wondering if it has something to do with the latest W10 update!? Finally I'm a happy camper!
A quick Google search revealed that there are others running WLM under Windows 10, and even Microsoft say it will run. In theory, it should have run before the latest updates were installed, so that is not necessarily the reason why it works now. Personally, I think eM Client is a much better free email client. Also, it gets updates, unlike WLM which has not been updated for close to two years.
Actually I had been using eM. I had two addresses (same ISP) and it would often throw and error, even though the mails would arrive in the non primary address fine. I got tired of closing the text box. Then yesterday I received a notification about the license being expired, yet the license I was using was good until 2017. The bad news is I'm back to Thunderbird, as Live Mail started saying "Can't view this message!" I dumped Thunderbird a few weeks ago since when you try to enter more than one recipient it doesn't auto select their address. I searched that problem, and at least for the version I was using, it was what it was! Fortunately I mostly use gmail so I can live with the Thunderbird inconvenience.
