Is there a mail server with a corporate cross-platform chat?

Question

Email

Colleagues, please tell me the implementation of corporate mail with an address book, a corporate chat (and so that you can enter the chat from Android, iOS mobile devices, and Mac, Win computers), and with the ability to view all letters from users (for bosses)? If this does not exist, then how can it be implemented at least without a chat (for example, raise a gabber)? Many thanks in advance for your answers!

Answer 1

Exchange + Lync, I can advise.

Answer 2

Regarding the chat - ejabberd + mod_archive
Mail with separate software (even if exim + dovecot)
Authorization via ldap for both, and so that the accounts are the same.

Answer 3

bitrix24?

Answer 4

Haven't tried it, but there is this www.synovel.com/collab/editions