Re: SMTPDataError: Looking back through our logs over the last year, I see 554 blacklist, 454 Throttling failure, and 454 Temporary Server failure.

A couple of observations from this:
1. It seems SES is not very strict with their error typing.
2. I wonder if it's a good idea to infinitely retry on a "temporary server error?"  But I guess we do have exponential backoff.