Airmail does a good job in allowing quick triaging of incoming emails, with great keyboard shortcut support, quick message filing, “snoozing” of messages, etc. However, it has some serious shortcomings that, at least from the responses from technical support, the developers seem to have little or no interest in correcting.
* It’s impossible to search within a single mailbox, making it extremely difficult to find messages in a glacially slow global search that may search 10s of thousands of message and returns hundreds of hits.
* GPG/PGP/Encryption “support” is through a non-supported 3rd party plugin that has numerous major bugs making it almost unusable. It hasn’t been updated in more than a year, and Airmail provides absolutely no support for it, nor are they willing to make any commitments to future encryption support. This is almost an unforgiveable oversight for a modern email client.
* Synchronzining mailboxes can be extremely slow, and mailboxes can get into inconsistent states requiring removal of all cached messages and full resynchronization of the associated accounts.
Airmail is definitely a more efficient app than Apple Mail from a UI standpoint, and with a little effort, could be made a superior product. However, the attitude of the support and development teams does not make me optimistic that this will happen.