Just for Clarification: I use NethServer as mailserver for myself and most of my 30 clients.
My mailservers do not use / need a “Smarthost”.
My NethServers and OPNsense firewalls - as acting internal DNS for my managed sites - do not use any external DNS as forwarders at all.
The only commercial mail system I ever trusted was Novell’s GroupWise. However, that’s almost history now… (It still exists…).
Commercial - as Oracle once called it in on an ad on the german Chip magazine - “Virus Exchanges” are not my thing, although i’m very good at handling them!
ProtonMail does have a good track record, I’ll admit.
But for legal reasons, most of my clients, typical SME sized clients, prefer to run their own mail / groupware systems.
Novell GroupWise was cool in it’s time. One of the few systems where a system administrator could not just give himself permissions and read a users mail… In that sense, it was quite popular and often used for state systems, where (here in Europe) stricter privacy rules are valid than say in Russia, China or America!
Another cool feature I haven’t seen on other systems is working, multiprotocoll file shareing with file locking… If an Apple user opened a file with AFP, it was locked for Windows users, Novell users (NCP) and NFS users. Same any way around…
Linux - and most other systems today still base locking on a very restricted view.
SMB is locked in it’s own island.
NFS is another island.
AFP is yet another island…
Windows isn’t any better iin this respect.
Although it’s true that SMB/CIFS is the most used protocoll nowadays, NFS is still one of the best between UN*X / Linux boxes with the least overhead.
