>the emails are only sent when the customer selects to receive an email, and we include a visible unsubscribe link.
Just for what it's worth, sometimes when a company's marketing is really obnoxious I'll mark it as spam just to fuck with them.
If there are enough people doing that, one could imagine that Google's internal filters would begin seeing the whole domain, or some random boilerplate string in the emails as an indicator of spam.
Have you started manually flagging messages as "not spam" on mass?
Just for what it's worth, sometimes when a company's marketing is really obnoxious I'll mark it as spam just to fuck with them.
If there are enough people doing that, one could imagine that Google's internal filters would begin seeing the whole domain, or some random boilerplate string in the emails as an indicator of spam.
Have you started manually flagging messages as "not spam" on mass?