Best upgrade to the Apple Mail on the market period. I have been using it for more than a couple of years. I also used Newton which was good but will be discontinued come late September 2018. Also, AirMail 3 and Spark. While all of the above are not bad, Mailbutler is still the best in terms of functionality, convenience, practicality and their great support team that is creative, thoughtful and innovative. Once Mailbutler comes up with iOS version they will simply be the best on the market for all-round Apple users. In the meantime, Mailbutler in Apple Mail remains the best email client for MacOS in my well informed if not so humble opinion.
Serious step back in usability. Their configuration web page now replaces the efficient Mail plug-in interface, and this web page is difficult to navigate and lacks several of the features and options previously offered by the plug-in: -- Avatar icons / Contact images in Apple Mail now are virtually non-existent. The previous version was EXCELLENT in locating and displaying user & company avatar icons. -- You now cannot choose the minimum size of attachments to trigger their upload to a cloud service. -- There is now MailButler advertising inserted in every outgoing email if you do not pay them a monthly fee. -- The optional MailButler menu bar icon ("Direct Inbox") now does absolutely nothing when it is clicked. -- This new version of MailButler is incompatible with the QuoteFix Mail plug-in. -- MailButler's Smart Mailboxes in Apple Mail are now gone.
These issues are just what I've discovered in the first 24 hours. I really hope the developer fixes all of these problems ASAP.