I've been with them for my private mailserver VPS for ~7 years now and the support in IRC and via the ticketing system has always been fast and friendly. The author talks about the KVM/slice setup in the post but they're still dilligently running all the openvz from legacy contracts. You can count on them being around years from now.
I followed the general outline of the ispmail tutorials at https://workaround.org/ispmail . Debian based, postfix, dovecot, mysql, postgray (spam mitigation), catchall for the entire domain and only access it from imap clients or ssh'ing in. Doing webmail seemed like too much work to keep things secure. I self signed all my certs since it's just for me and very easy to set up and maintain (unlike letsencrypt over the same time span).
