Interesting, although I have to admit, this brings back memories of dealing with sendmail rewrite rules back in the 90s when I had to maintain a uucp based mailserver as an intern ;-) I’ll have look, thanks!

Yeah, well, empirically, I had repeated issues with t-online and gmail recipients mostly. And I was never sure if it was my config, my IP (hosted on netcup), or something else, but it required constant attention. And that problem should really be gone with an smtp as a service (hopefully).

But maybe I’ll have a look at mailu anyway…