TL:DR; can you recommend an email provider that supports sieve and works for email based development and doesn't block/reject any valid emails?
Okay. I've been doing email based development for over 25y now using the amazing, multiple times award winning internetprovider #xs4all.
Sadly, xs4all was killed by the Dutch telecom giant #KPN. Email-wise this means that #sieve support was dropped and a helpdesk is virtually non-existing.
So I switched to @freedominternet but they don't have the skills to do email and outsourced it to #soverin. They do support sieve (sort of via a clumsy web interface), but they keep rejecting valid emails (some four a day) sent to development lists. The helpdesk takes weeks to respond with a useless answer. This is terrible.
Self-hosting (as we did in the old days) might be an option but I'm not up to date with what is needed. A #Guix recipe for an email server setup with dovecot and sieve would be amazing here (but knowledge on how to create that seems hard to get <https://lists.nongnu.org/archive/html/help-guix/2024-09/msg00017.html>)
Anyway until we have that, any amazing email provider can you recommend?