Excellent App for my use on Mac-mini, Macbook Air, and Iphone 6. Pluses: 1) Fast--fast--fast sending and receiving emails! 2) Organization and layout for easy viewing of emails 3) Options--options--options! Delayed sending, read receipts using Mac plugin and on IOS devices purchased BEFORE May 11, 2017 4) Tech support-David was great at 7:00am on July 4th, 2017 Minuses: 1) Weird bug with auto-reply vacation messages Airmail is more effiecent and organized than the standard Apple Mail app that comes with the Mac and IOS devices. I cant say enough about the speed of sending and receiveing emails. I havent had a problem with syncing accros devices or adding accounts. Great layout-I hated the confusing layout on the standard app that comes with Mac and IOS devices. I also tried using the google and yahoo apps as well as their desktop mail apps. Read receipt reminders--A great option for those who get tired of hearing "I didnt get that email." Buyer beware, read receipts are only available for your Iphone and Ipad if you purchased BEFORE May 11th, 2017. On Macs you have to download and install a read receipts plugin. Delayed sending is another great option that gives you the opportunity to rethink that email before you send it. Tech support-see above. David quickly and efficiently responded to my question. Auto-reply vacation message. Whats up with that? I couldnt set up an auto-vacation reply directly in the app on any of my devices. The reply message wouldnt save on any of my devices. The work around was to go straight to my google and yahoo account pages and set up my vacation auto-reply there. Just a weird bug in an overall great app.