I don’t recall the exact date, but when I worked at Digital Equipment Corporation (DEC), 1994-1996, I got a beta version of Exchange 4.0 in late 1995. Having worked with MS:Mail, VMS Mail (ALL-IN-1), and several other email systems I really wanted to see the new mail server from Microsoft.
So using my DEC AXP150, running a true 64-bit processor in 1995!, test box running Windows NT 3.51 64-bit. I installed my 1st version of Exchange 4.0 beta (64-bit also) and started down the path of being a Microsoft Exchange consultant and expert.
Initially, this was just a test system but our team of ~30 quickly moved it for our primary communications. We were on the Microsoft PC Apps support team and really didn’t like the character only messaging systems we had been using. Within a few months, it expanded to the PC hardware support and other teams and when I left DEC, in early 1996, we had over 200 mailboxes on two different Alpha based Exchange 4.0 beta servers. When I was leaving DEC I chatted with our corporate IT staff about their planned roll-out of Exchange, which had Tony Redmond (fellow Exchange MVP) on the team. It wasn’t until around early 2000s that Tony and I reconnected and realized we had talked about Exchange about 10 years earlier when we were both at DEC.
At home, where I ran a 12 node BBS and mini ISP, I continued to run NetScape Mail until Exchange 5.0 came out with OWA support in 1997.
My 1st email system I ever setup was actually about 30 years ago, in 1986 when I was sysop on multiple WWIV BBSs that were integrated into the FidoNet. Back in those days you could still send an email around the county or world, but it would take many days to get to some locations. We were limited to 300 baud, or about 300 characters per sec, and long distance phone calls were expense, but the rates dropped in the middle of the night. So Fido net would store and queue up message during the day, then at a schedule time when long distance was cheaper it would call a BBS in another city. This process would repeat until your message got from your BBS to the user on the target BBS. It was common for a message to take days to get across the county initially, but hubs were setup and Delphia & Compuserve start providing quicker routing in the early 90s.
Today, we commonly see single emails that were many times the size of our entire mailboxes in Exchange 4.0. We started out with 10MB mailbox I believe on Exchange 4.0 at DEC, now I host mailbox for friends and family on Exchange 2016 out of my house that have a 10GB limit by default 🙂