hMailServer: “connection to the database is not available”

Outlook just gave me warnings that it could not connect to my local mail server. RDP’ing to the server, I wanted to start hMailServer Administrator, but it only responded with an error message:

The connection to the database is not available
ADO: Cannot open database “hmailserver” requested by the login. The login failed.

Since I had rebooted the server after Windows Update insisted, I blamed Windows Update.

I looked into the log files, which showed repeated error messages

“ERROR”    748    “2012-07-17 18:18:19.235”    “Severity: 1 (Critical), Code: HM5028, Source: ADOConnection::Connect, Description: Error when connecting to database. Microsoft OLE DB Provider for SQL Server Cannot open database “hmailserver” requested by the login. The login failed. Check your database settings in hMailServer.ini.”

No event log entries could be found relating to this error.

This time, however, there seems to be a problem when hMail cannot connect to the database during startup. As this hMailServer issue indicated, restarting the hMailServer service (with SQL Server already running) was enough to solve the error.