In SharePoint 2013, you will be amazed to see that , there is no option available in UI to enable email Alerts for Task List.  However, this can be easily achieved through Powershell commands. Below are the piece of code which enables email notification.

$spsite=Get-SPSite “http://mysite/”
$spweb=$spsite.OpenWeb()
$splist=$spweb.Lists.TryGetList(“Tasks”)
if($splist -ne $null)
{
$splist.EnableAssignToEmail =$true
$splist.Update()
}

In a similar way, if you want to disable the email notification, please use the below Powershell scripts.

 $spsite=Get-SPSite “http://mysite/”
$spweb=$spsite.OpenWeb()
$splist=$spweb.Lists.TryGetList(“Tasks”)
if($splist -ne $null)
{
$splist.EnableAssignToEmail =$false
$splist.Update()
}

Happy SharePointing 🙂 Feel free to comment if you find the above information useful.