So, nothing special.

I experimented with my vServer, set up Postfix (read: replaced exim as smarthost client and set up Postfix as regular mail server).

Being technically interested, I also set up SPF and DMARC for my existing domains. Then I set up DKIM for my vServer (was already setup on my regular domains by my web hoster), together with SPF and DMARC.

I also contacted the all-inkl support to move my servers, so I could finally update Nextcloud (since MySQL 5.x on the old servers would no longer be supported).

Finally, I found about about DANE. Unfortunately, I can only set this up on my vServer, since it required to put the certificate hash as DNS record. Using letsencrypt certificates, which are renewed every ~ 90 days, this makes it very ugly. On my vServer, I can configure the ACME client to reuse the key (has stays the same, DANE record stays valid). However, with my web hosting, this is not an option. Oh well.