I have an old, shared webhost with a lot of users who want to forward emails to gmail, but aren't willing to pay for gsuite to get a custom domain and stop usin

I have an old, shared webhost with a lot of users who want to forward emails to gmail, but aren't willing to pay for gsuite to get a custom domain and stop using my webhost for forwarding. Plus gmail isn't very good with custom filter rules. I had most of the traffic moved to procmail/spamassassin, and added greylisting, but there is still enough spam going to gmail that I was having deliverability problems. These show themselves as gmail giving soft fails and a huge queue building up. My current solution is 2-fold: 1) It turns out that gmail is likely to soft-fail the spammiest incoming messages. So I have a script that deletes them from the queue, with rules that match addresses that get the most spam. That way my IP only gets 1 badness point per spam message, not dozens for all of the retries. 2) I moved the outgoing email I care about to a different IP.