Gmail, IMAP, and “Account Exceeded Bandwidth Limits”

Apple Mail is failing to fetch mail from Gmail, with the following error:

200908261034

Googling this error message shows lots of other people running into the same problem. Some bandwidth limit on Google’s side is cutting me off. When this happens, I’m put in a penalty box and not allowed to connect via IMAP for some period of time.

I’m not using mail excessively. I don’t get a lot of big messages; I do get a lot of spam but there’s not much I can do about that.

Other users have complained to Google and gotten nowhere. I’m not paying for this service so it’s not like I can call a customer support line and threaten to quit. What can I do?