I find it very unhelpful that I cannot revert to 'Unknown' (the GUI will not let me, nor is there a CLI command). I have own scripts outside of Plesk which manage the certificates for dovecot, postfix and ProFTPD.
@IgorG You are surely right regarding "default certificate" - BUT the internal mechanism changes:
Dovecot default certificate always used to be at /etc/dovecot/private/ssl-cert-and-key.pem ; as soon as I (mistakenly, or as a trial) select something for "Certificate for securing mail", then Plesk adds a config file /etc/dovecot/conf.d/11-plesk-security-ssl.conf, which refers to /etc/dovecot/private/dovecot.pem. This I could reverse back by a later custom file of my own, e.g. /etc/dovecot/conf.d/50-custom-security.conf
Postfix is a real problem: Plesk generates both main.cf and master.cf, now switching the cert file from postfix_default.pem to postfix.pem. The problem here is, that Postfix does not have any "conf.d" directory, and the only 2 config files it does have are both generated by Plesk. So I see no way to compensate for what Plesk is not allowing me to do (revert to "Unknown").
In any case, I could never delete whatever certificate is assigned in Plesk, because Plesk sees it as being in use. Nor do I feel good with just overwriting the Plesk certs "dovecot.pem" and "postfix.pem" - whenever Plesk regenerates it's config, my .pem files would get overwritten.
What really gets my goat is when a system defines it's own way of doing things and does not give you any opt-out possibility. Look at the choice of word: Not "None" but "Unknown" - implying that Plesk
intends to do this - whether I want or not. I find that disrespectful, and an unneccessary straight-jacket.
SO my question: What Database entries do I need to edit to get back to heavenly "unknown"?
Thanks! Tim