There are a few comments/pieces of feedback on attachments. But other than the composer, it's another bit of Airmail that could do with a proper revamp. Feels like an afterthought at the moment.

— Attachments at TOP of mail, not at the bottom or randomly in the email chain... Apple Mail sticks them at the bottom too and it's hella annoying, especially if the chain is long or when you're hunting for an old attachmrnt somewhere
– Attachment/file view and/or manager. i.e. being able to view an inbox folder or sender as a file manager folder to organise attachments.
— Attachment reminder: "It looks like you meant to attach something" reminder would be good (though not essential)

I have to switch to my outlook webmail whenever I want an attachment at the moment :(