Ive said it before...
Airmail is hands down the best email client for the Mac... ever. And now with full OS and iOS support, its even more perfect. Accounts sync with iCloud so you set them up once and they easily migrate to all your devices. Brilliant! Not sure how they can improve it, but I always look forward to new releases. I use it with Exchange, GMail and multiple IMAP accounts and it never skips a beat.
clance-man about
Airmail - Your Mail With You