Suddenly without prior notice we get an email: "Your account xxx has been temporarily disabled". Total blackout of all our email delivery.
Takes multiples emails and support ticket to get re-instated. Apparently we went above some "complaint rate threshold is 0.05% or lower" threshold, ad boom auto-disable. We now think (but guessing) our own users were complaining about contact form message spam getting through (as it seems google v2 recaptcha is easily spammed these days).
Not faulting MG for having spam protections in place, that's great. One one think after being a client for nearly a decade of clean email sending, you'd at least get a notice about unusual activity before a blanked account deactivation.
/rant
Any alternatives folks have had good relations/practice with?