Customer requests for quotes, Paypal/Stripe security messages, lots of other important emails go to spam.
See e.g. https://github.com/nh2/gmail-spamfilters-paypal-security-mes...
For a while now I suspect that GMail has some bug with its own group email addresses:
When somebody sends an email to our GMail group email address team@example.com, it shows up in GMail as "Sombody via team@example.com". Of course, teamexample.com receives both spam and non-spam.
I suspect that when we mark spam that comes "via team@example.com", GMail learns that as "things 'via team@example.com' are often Spam", even though info@example.com is a Google Groups email.
And by now, everything that comes 'via team@example.com' is marked as Spam.
So it seems that when we mark an email that arrived at team@example.com as Spam, Google punishes its own Group email address, instead of the sender.