Hi Marco,
> - is it psosible with rspamd to rate limit ougoing emails?
It's possible. The `user` keyword applies a global ratelimit
per-authenticated-user. Rates for individual users are possible using
custom keywords. If you don't use authentication but can identify
distinct streams of outbound mail somehow it is probably still workable.
See
https://rspamd.com/doc/modules/ratelimit.html - especially
sections about composable and user-defined ratelimits.
> - is it possible to serialize outgoing emails per mx?
> This feature is missing, natively, in Postfix.
> PowerMTA has and they call it "MX rollup"
Not clear to me what this is; seems to be MTA feature. Rspamd can send
a signal to your MTA that it should perform some certain task but that
is all.
Best,
-AL.