"- Your engineer said to me "we took down 600 old accounts and are reviewing our contact policies going forward" and "there are still plenty of other customers who are listed generically as bouncing so we will have work to do here"."

(snip)

"That tells me that you knew that you were sending to old accounts and that your bounce handling was either not great or non-existent."

Yes, that is exactly right.

I have instructed everyone to be as liberal and forgiving of non-payment and failed contact as possible. These people, who were paying customers, have data stored here for safekeeping and we're not going to trash it because we haven't heard from them in 3 months or their email bounced.

I can give you hours of stories of customers who came back from military deployment, came back from depression, came back from prison, came back from financial ruin ... that contacted us, beyond all hope, to see if we still had their account. And we did.

After 21 years of doing this are there a few hundred accounts that we are giving extreme benefit of the doubt to ? There certainly are.

Bottom line: our duty of safeguarding customer data trumps this weeks fashionable spam heuristics.