SQL Server alerts not sending notification emails to the operator I have setup few SQL Server alerts and added Operator to notify if any alert occurred.

I just noticed that couple of alerts did occurred but we didn't receive any alert email. I did send a test notification email to the operator and it worked and we received email. 

Any idea why we are not getting email alerts when actual alert occurred?

Nothing in Database Mail Log.

The SQL Server is part of the Availability Group and I'm only providing email name in operator not doing any 'Net send address' or 'Pager e-mail name'. Also all the alerts are listed on the Properties of the Operator.

Alert History got 'Number of occurrences :266' and Date of last alert is yesterday 29th June but I didn't receive alert email at all. Even Operator history got no history at all (Never e-mailed).
Check SQL Server Agent Properties: on the "Alert System" page, is "Enable mail profile" checked?

Sometimes with new installations, after I set up options on that page I've found notification emails for alerts aren't sent. A restart of the SQL Agent service often addresses that issue for me. - dave-mason

An article that explains more details: How to setup SQL Server alerts and email operator notifications by David Bird - joshua-washburn

Helpful debugging queries: Notes on debugging Database Mail problems by Kenneth Fisher - erik-darling