I have an issue with the search box as well. It is available when I first launch the client, but simply disappears after some time. Restarting Airmail brings it back. I'm on a late 2013 Retina MacBook Pro running High Sierra. The laptop is connected to a Thunderbolt dock 24/7. I think it could be happening after it goes to sleep and I wake it up, but that I'm not 100% certain. I will monitor this more closely and see if I can replicate it.
I have the same issue. I am able to somewhat reproduce the issue. I using a 15" 2017 Mac Book Pro running MacOS 10.13.3 and AirMail 3.5.4. At work, I connect my Mac to 2x Thunderbolt Displays via a Thunderbolt 2 to Thunderbolt 3 adapter, and at home I use a Thunderbolt 3 dock. The search bar almost always disappears when I wake my Mac from sleep by opening the lid and then immediately plugin the Thunderbolt 3 / USB-C cable at home or at work, so it's something related to waking the computer after it's been asleep for an hour or so and then connecting it to external displays. The only way to get the search bar to reappear is by quitting and relaunching AirMail. I often have an issue with AirMail not displaying when clicking on the App icon in the dock. It's like the window has moved itself completely off the screen, but I am able to bring it back on the screen by clicking on Window --> Zoom in the toolbar at the top of the screen. Hope this helps.
This is also an issue for me no search button- very frustrating. Even when you go in to the menu bar and go to edit/search all messages it goes straight to the search results and says no message found - there is nowhere to input your search terms. I am using Airmail 3.5.4 on a macbook air v 10.13.3
on 22 Mar, 2018 12:55 PM
I'm also having the same issue. I'm using a Dual Screen, but it's set to mirror, so I don't know why there's an issue. But so many of us are having the same problem, it seems like it should be a high-priority fix. I haven't been able to let go of Mail Mac, simply because I need its search capabilities. It's very frustrating.