I said yesterday that the main faults of Airmail for iOS are actually the faults of email itself. Despite consistent development and improvement, I can't totally say the same of Airmail for Mac. Interestingly, though, I find that two of Airmail for Mac's major shortcomings — search and threading — illuminate the larger problems with email as a whole. (I almost said "email as a communication medium", but not truly being used for communication is one of the problems.)
Everyone with an email account has at one point or another struggled with email organization. The "modern" approach to the problem is to punt, only performing coarse organization (sometimes as basic as archived vs. not archived) and trust search to handle the rest. This is very much The Gmail Way, but given its Gmail roots, Airmail's search is surprisingly lacking. Want to search the current label or folder? You'll have to type its name and hit return to generate a search token, and then begin your search. Found the message, but not the relevant term in several paragraphs of text? Type your keywords again as you enter battle against Airmail's recalcitrant intra-message search.
Often my email searches target a particular piece of information: a flight confirmation number, a receipt, the time and location of an event. Tools like Google's Inbox app attempt to make these, rather than messy messages, the units of email. Yet a proper solution isn't to extract meaning out of chaos, but to begin with structured data. Convincing corporations who use email as a one-way street to adopt such a model is a big ask, but one that the likes of Google, Facebook, or even Apple could take on.
Back to Airmail, my greatest frustration with it is woefully poor threading. Like most modern mail clients, it tries to collapse earlier quoted messages, but unlike even Apple Mail, it fails more often than not. The problem here is that, especially in a work environment like mine, people treat email like extended chat. It would be pathological to repeat every previous message in a chat, but it's the default for email. My coworkers are wedded to Exchange email, and I'm still more likely to convince them to move to a chat-centric solution like Slack than to alter their quoting behavior.
Nobody can singlehandedly fight the entropic decline of email from a useful communication platform into a point-to-point transfer of unwieldy blobs of text. Bloop, the makers of Airmail, are doing their part to make those blobs easier on the eyes and more versatile. They are striving to build a better band-aid, while modern email continues to be death by a thousand cuts.