What you’re seeing
- A mailbox database shows Dismounted and refuses every attempt to bring it online.
- Outlook shows Disconnected for all users on that database, while users on other databases are fine.
- Webmail displays an error instead of the mailbox for affected users.
- Event log entries mention a dirty shutdown, missing log files or a failure to mount the database.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The database was left in a dirty shutdown state after a crash or power loss, and the transaction logs it needs to recover are missing or damaged.
- The volume holding the database or its logs is full, so Exchange cannot open it safely.
- Antivirus software quarantined or locked a log or database file.
- The storage holding the database was disconnected, failed, or now presents under a different drive letter or path.
- The Information Store service is not running correctly, so no database can mount.
Why it matters
Every mailbox on the database is offline until it mounts, which can mean an entire department or company without email. New mail from outside waits in queues or bounces, calendars and shared mailboxes become unavailable, and staff cannot access years of correspondence. The pressure to get mail back quickly also leads to risky choices, and some recovery methods permanently discard data if used incorrectly, so careful diagnosis matters as much as speed.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
Is our mailbox data lost?
In most cases no. The data is still in the database and its logs. Some aggressive repair methods can discard data, which is why our engineers confirm the cause and agree the approach with you before changing anything.
Can people keep working in the meantime?
Users in Outlook cached mode can usually still read mail already downloaded to their computer. New messages wait until the database is back online.
What if our backups are old or not working?
Tell the engineer at the start. Knowing your backup position shapes which recovery options are safest, and it is assessed before anything is changed.