Sql-server – Setting Alerts for Autogrow

is there a way I can send messages directly to the Database Mail queue using Service Broker

When you invoke sp_send_dbmail that is exactly what is happening.

I want to setup an EVENT NOTIFICATION for SQL Server, and I'd like to send e-mails to operators for each message on the queue

Then do just that. Create an activated stored procedure on the queue of your service that receives the notifications and have it RECEIVE the message and invokes sp_send_dbmail.

I think you are trying to 'cut out the middleman' and have the EVENT NOTIFICATION send the notification directly to the DB Mail queue. That is not possible because the code that handles the messages arriving in the DB Mail queue expects the messages to have a certain format (ie. the one created by sp_send_dbmail). The messages sent by Event Notifications would have a completely different format and the DB Mail processor would choke as it does not understand them. In order to prevent exactly such situation Service Broker services are bound to specific contracts and DB Mail service does not accept the http://schemas.microsoft.com/SQL/Notifications/PostEventNotification contract used by Event Notifications.

I can think of a few questions about this implementation that I would want to know before continuing:

1. What happens if, somehow, microsoft creates an object with the exact same name in a new version?

2. If databases are migrated to a new server, how will anyone know that there's something in master to migrate?

3. What happens if your objects corrupt the master database?

4. What adverse affects would having extra data in master have on the instance?

5. What would happen if an in-place upgrade was performed on this instance? (ie, upgrading 2008 to 2008 R2)

6. How would restoring the entire instance from backups be affected?

Most of these I don't know the answer to, but they're questions that come up when I contemplate putting objects in master.