Create Exchange Mailbox Databases on Exchange Server

Not gonna lie—Exchange mailbox databases used to intimidate me. Back when I first deployed Exchange 2016 on a Hyper-V lab setup (ThinkPad P52, 32GB RAM, running nested virtualization), I winged it. The database creation felt straightforward, but the devil was in the details: log paths, mounting delays, and mailbox provisioning quirks.

This post isn’t a polished tutorial—it’s a walk-through of how I typically set up mailbox databases on Exchange Server, what tripped me up, and what I do differently now.

Why I Needed a Fresh Mailbox Database

I was spinning up a new Exchange Server for a mid-sized org—around 150 users. The default database was fine for testing, but I wanted to isolate departments into separate databases for better retention policies and backup strategies. Plus, I’ve had bad luck restoring from bloated default DBs in the past.

Step-by-Step: What Actually Works

1. Open Exchange Admin Center (EAC)
I usually start with EAC unless I’m scripting in PowerShell. Hit https://<YourExchangeServer>/ecp, log in, and head to the “Servers” tab → “Databases”.

2. Click the “+” to Add a New Database
Here’s where you name it, pick the server, and set file paths. I always double-check the log file path—once, I left it on the system drive and it filled up overnight. Lesson learned.

3. Configure Limits and Retention
Most guides skip this, but I tweak mailbox size limits and retention here. I’ve seen users hit quota caps within weeks if you leave defaults untouched.

4. Save and Mount
After saving, the DB isn’t mounted yet. I mount it manually—sometimes it takes a minute, and the UI doesn’t always show progress. The screen just sits there… black, silent, almost mocking me.

5. Create Mailboxes
Once mounted, I jump to “Recipients” → “Mailboxes” and start adding users. I tag the database explicitly so I know where each mailbox lands.

Bugs and Gotchas

• Mount delays: On one setup, the database refused to mount until I restarted the Information Store service. No errors, just silence.
• Log file placement: If you’re running on SSDs, separate the DB and logs. I’ve had corruption issues when both sat on the same volume during power loss.
• PowerShell quirks: If you’re scripting, New-MailboxDatabase works fine—but don’t forget to run Mount-Database afterward. I’ve skipped that step more than once and wondered why mailboxes weren’t provisioning.

What I Do Differently Now

• I always pre-create folders for DB and logs—Exchange doesn’t do it for you.
• I script the whole thing in PowerShell for repeatability. GUI is fine, but for scale, scripting wins.
• I monitor mount status via EMS instead of waiting on EAC’s UI.

Final Thoughts

Creating mailbox databases isn’t rocket science, but it’s easy to mess up if you rush. I’ve learned to slow down, double-check paths, and always test mail flow after provisioning. A single typo in the DB name can cost you an hour of debugging—ask me how I know.

Ever had a mailbox database refuse to mount for no reason? Or accidentally provisioned 50 mailboxes to the wrong DB? Drop your war stories below—I’m always curious how others handle Exchange quirks.