Error: 9245, Severity: 16, State: 1. / "During the last time interval X query notification errors were suppressed"
It's the simple built-in alerts that you can configure in SQL Server i.e. (EXEC msdb.dbo.sp_add_alert @params) - it emails the DBA team when that error is captured.

Since this particular "cause"  is not exactly threatening the health of the server I was wondering "other than a mailbox rule" if there was a way to "omit" these particular ones containing "notification errors were suppressed" - so basically that they're not sent at all.