Use color labels
I use an independent mail provider. In Apple Mail you can put multiple labels in different colors on one message, what I use a lot. But when I use a label in Apple Mail, Airmail just put a star on the mail despite how many labels/flags and which color I put on a message in Apple Mail. Please fix that. As I had to buy your app to find this out, because there is no trial version.

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Monique Clark commented
I can't believe this isn't a feature :(
The way I run my business depends on being able to colour code emails. I have done it this way (in Gmail) for years. I love the idea of Airmail but this is a total deal breaker for me and my employees.