My Problem

Recently our emails alerts stopped working in SharePoint 2013. Or maybe I should Say recently we noticed that our email alerts stopped working. We added an additional server to our SharePoint farm a couple of months back and this caused the emails to be not sent out anymore. The initial email with the following title is still sent out:

You have successfully created an alert for ‘Documents’

but the alerts themselves are not.

Your Solution

So how does this work. The initial email is sent by the web front end server and this is sent straight away. The email alerts are sent by a timer server. In my case this is the new server that we added.

Both servers try and connect to the smtp server configured in SharePoint. In the SharePoint logs on the failing server I found the following errors:

Cannot connect to SMTP host

So all we had to do is add the new server to the white list on the smtp server allowing it to send emails.