Thank you for your answer Nataliya,
I know that Plesk release notes refer that Plesk supports versions of mailenable you just mentioned, but I also know that newer versions of mailenable can be used.
For example, we use Standard Version: 3.63 instead of 1.986 mentioned in release notes, and it works just fine.
So, I would like to know if anyone has tested Mailenable Professional 4.16 version with Plesk.
Thanks again,
Giorgos