You have found the right place! @Dmitry I want to give you a big welcome to NethServer Community by all NethServeriziens!
I think that many people in this community have migrated from Exchange to NethServer.
Personally I have quit Exchange Server many years ago so feel free to post your question and, if you haven’t done yet, take a look to this post:
I hope that in this community you will be able to find aswers to your question and help you are looking for.