Dear Sir;
My name's Javier Aguilar, I'm Systems & Telecom. Engineer with +20 years experience in Systems Administration, IT projects management, server management, DataCenter management, Help Desk, Networking engineering design, deployment and troubleshooting, LAN/WAN/SD-WAN/MAN management, and other IT topics.
I suggest Zimbra Collaboration Suite, it has everything you need, in addition to a very complete user interface, it is very fast for searches, and it performs a very high compression of the mailboxes, which reduces their disk space and also , does not increase uncontrollably the consumption of disk space as do other applications. I have been implementing this mail system for more than 11 years, from version 4 to the latest version. It is the best option in an alternative business mail system to MS Exchange, and as I indicated it meets everything they need and exceeds it.
I'm ready to start with your services, but if you like contact me by chat before making a decision to know details about your issue. I'm online right now.
Best regards,
Javier Aguilar
IT Business Corp.
Montevideo, Uruguay, South America (GMT-3:00).