[CentOS] Which is better? Microsoft Exchange 2016 or Linux-based SMTP Servers?

> Andrew, you should understand that you are talking to experts in Linux
> here.
>

No, i was talking to the OP who is seemingly not an expert. Advising those
who not competent that they can set up and run their own mailserver is
probably negligent.

Whipping up Exim and Dovecot for your own private email server is one
thing. Setting up for an organisation is a completely different story.
Mailservers are extremely hard to do well and a job for a specialists. Just
making mail deliverable requires specialist knowledge and keeping an
up-to-date and effective spam filter is near impossible nowadays.