SharePoint Alerts not working properly, the users get confirmation email, but they do not receive any alerts.
There could be several reasons for this happening, in the case I worked on we had previously recreated the WFE servers for a medium farm and everything looked OK after testing, but once users tried to configure new alerts, this issue appeared.
First thing to do is check to see if there is a "Immediate Alerts" SharePoint timer job definition, if there isn't one use the following commands to create one.
stsadm.exe -o setproperty -url http://SERVERURL -pn alerts-enabled -pv true
stsadm.exe -o setproperty -url http://SERVERURL -pn job-immediate-alerts -pv "every 5 minutes"
Restart the SharePoint Timer Service after completing this.
Still not working? Determine which account is running the SharePoint Timer Service and make sure this account is added to the SharePoint Administrators Group (Central Administration\Operations\Security Configuratio\Update SharePoint Administration Group.)
Also check to see if that Timer Service account has access to the Content Database on the SQL server.