> My address sometimes gets blocked as coming from a dynamically
> assigned IP address, even though the IP address is a static address.
Okay, that's odd. But what could the ISP do about it?

> list services that use PBL are not a good idea and serve the interests
> that are exactly opposite to the Devuan philosophy.
It's a trade-off, as usual. I don't know how much actual spam gets filtered out, so I can't tell whether the trade-off is worth it.

> I'm not letting ISPs take over users' freedom to host their own MTAs,
> and you should not either. :P
My ISP doesn't filter my connection, so they're holding to their end of the deal. Beyond that, there's really nothing they could do about foreign MTAs refusing to accept mail from here.
But I still want to run a local MTA, and I do, as my mail headers should confirm.
I am just forced to send outgoing mail via a relay (incoming mail is handed to postfix by fetchmail).
It is unfortunate, but still the least painful feasible way of doing EMail these days, given the constraints, apart from throwing money at it.