I just needed to test if I can send emails to gmail accounts form my selfhosted mailserver without them getting put into the spam folder.

I'm using that email for ~6 months now, I haven't yet send an email to gmail... I checked. And I use email quite a lot actually.

That's a good point but at least Google won't be able to disable your gmail account and lock you out of all the accounts and media you had tied to it.