Which own mail server to choose?

Question

Mail server

Good afternoon. There was a question of a choice of own e-mail server in office. Now we use corporate mail gmail. But the functionality is missing. We need something close to exchange in terms of capabilities, but without the need to fence the domain. There are plans to expand to 100 mailboxes. I would like to install everything out of the box once, configure and occasionally maintain.

Answer 1

I would advise you not to contact your mail servers. Decisions installed and everything does not happen. The constant war to pull your domains / IPs from blacklists is definitely not worth it. And it is logical that you will need your own domain to register, and even a white IP with the ability to register a reverse zone on a higher dns (which not every provider wants to do).
So my advice is mail for the Yandex, Google, MS domain is your choice.

Answer 2

Out of the box - use other and paid solutions from gmail, yandex and others like them.
Not out of the box - postfix (the agent itself on the server) + dovecot (for the sake of imap, "like an exchange") + spamassasin (anti-spam) + sasl (authentication module, depends on how your authorization will be) + clamav (antivirus) + dkim (signatures) + in DNS register spf for your domain.
In this case, you will have to follow the updates of the software, both mail and auxiliary (for example, openssl) and the server itself. And eat a couple of dogs on configuring what is written.
I also note that there are alternatives to the specified software: postfix - exim, dovecot - courrier at least. You will also need to install additional software in the form of fail2ban, and self-written scripts, f2b is not enough for you and you have ipv6 open. And to the heap correctly configure iptables and ip6tables.
In order to file - put samba and make some kind of rules for users.
You need your own mail server if you understand why you need it. Plug-ins darkness for every lover. "Pull the server out of blacklists" - hit users (if you have a password change policy for users and passwords will be from 8 characters in different case and you won't have to use numbers) and write the correct configs (prohibit relay, enter white-gray-black lists) .

Answer 3

it doesn’t happen, occasionally serve, either paid or free, but in the question itself it’s not clear what you are missing, look at zimbra mdemon