FYI I just tried running the update from Plesk Onyx 17.8.11 to Plesk Obsidian 18.0.20 and get the same error at the end:
Exception: Failed to solve dependencies:
plesk-mail-pc-driver-18.0-2.centos.7+p18.0.20.1+t191029.1140.x86_64 requires postfix >= 2:3.4.5
Error: The Yum utility failed to...
As someone who hosts many sites and administers them via the wonderful Plesk admin, I am by no means a system or Unix admin. I do enough to get around but will resort to real help from a Unix admin when needed. I've heard great things about Varnish and often wondered if it would ever come on a...