G'day Renai - I know, it's a necro-post
I'm rather disappointed to not see more imagination here. So...
I use and totally recommend Fastmail. It's an Aussie webmail, about 16 years old now, and currently resides at https:\www.fastmail.com. Rather than me doing all the spruiking, you should look at their front page. However, the short story is that it supports POP and IMAP so you can have either a simple client pointed at their server, ot several clients all synchronising with their server.
I used to use and recommend legacy Eudora, but as it's no longer supported or developed, it is no longer secure. So I changed to Gammadyne Clyton which is the nearest lookalike to Eudora and works in nearly the same way. It supports both POP3 and IMAP4. Plus, it natively supports TLS 1.1, and will soon be upgraded to support TLS 1.2. And if I choose, it can be set to gracefully fail if the other end is not secure... The point here being that with Clyton in my box and Fastmail in the cloud, my email enjoys all the end-to-end encryption as a web page.
IMHO, Fastmail has no downsides. Clyton is, however, somewhat immature. It does do what I want, but lacks polish. On the upside, help is a very welcome personal approach, Greg Wittmeyer himself sorts it.
Unfortunately, Clyton does need a Windows box. Having said that, I am surprised you can't find this type of client in the Apple world. But maybe a Windows box with a good client would be infinitely preferable to Gmail+Outlook...