Why is there so much outbound traffic from Airmail 3 (from Bloop)? I have been using Airmail 3 (highly regarded email client from Bloop that you get via the Mac App store) for some time now, but I am not sure how trustworthy they are.  What concerns me about the app is how much outbound traffic there is.   I use the Little Snitch firewall so I can see how much traffic is coming out of Airmail 3.  What I see is close to 1GB over a period of one year.  This may seem reasonable at first blush, but I almost never use Airmail 3 to access email.  My email provider is Gmail and I access this service through the mail.google.com website for 99.9% of the time.  So the question is what is all this data that Airmail 3 is sending?  Is it just from the handshake protocol of Airmail asking Google if there is new mail in my inbox?  

Of asked Airmail 3 support and they claim to not store any user data (except under one exceptional condition that I did not trigger).

So I don't know what is going on, but I don't like all this outbound communication.
Privacy Policy and EULA

You should read Bloop SRL's Privacy Policy and End User Licence Agreement.

Bound by the GDPR

As an Italian organisation, based within the European Union, Bloop SRL is bound by the General Data Protection Regulation which should give you some reassurance.

No absolutes

However, no-one here can answer with absolute certainty that you can trust your information with the organisation. Policies and organisations can and do change.