Hey,
blacklist is the one place you don't want it in if you want mails delivered
Did you take a look at [1]? Do you have any specific questions about the rules system?
[1]
https://pmg.proxmox.com/pmg-docs/pmg-admin-guide.html#chapter_mailfilter
edit: ohh sorry, didn't read the title. If you give the rule the allows your exceptions a higher priority than the blacklist rule, it should work.