Solved: SharePoint 2013 custom workflow generates duplicate email notifications

Imagine this scenario:

You have a custom SharePoint Designer workflow attached to a list or a library in SharePoint 2013. The workflow runs when an item in the list/library is created or modified, and one of the steps in the workflow is to send an email notification to a user or a group of users. The workflow runs as expected, but your users are telling you that they’re receiving duplicate email notifications. How do I get rid of the duplicate emails?

Solution:

If you check the workflow history, you will probably see that every time an item is added or modified, the workflow runs twice. That’s why you’re receiving two email notifications. But why is the workflow running twice for each item?

The reason for this is timing. If your workflow is very short and the SharePoint server is very slow, the first instance of the workflow may finish well before the item is fully saved and committed to SharePoint. As the item is being processed, the workflow event receiver can fire again, and start another instance of the workflow.

The solution for this problem is to add a step at the end of your workflow which will pause the workflow for a few minutes – I usually set it to 5 minutes and that seems to solve the problem.

Finding out where SharePoint email alias is used

Recently, a question came up in the SharePoint TechNet forums regarding document libraries with incoming email enabled.  If you only know the name of the AD contact for the library, how can you find out which document library or list it’s pointing to? 

Here’s a straightforward PowerShell script which will iterate through every site collection in every web application and return the names and email aliases of every list that has an active email alias specified.

[System.Reflection.Assembly]::Load("Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c") | out-null

[void][System.reflection.Assembly]::LoadWithPartialName("Microsoft.SharePoint")
$oContentService = [Microsoft.Sharepoint.Administration.SPWebService]::ContentService;

[Microsoft.SharePoint.Administration.SPWebApplicationCollection]$waColl = $oContentService.webApplications;

$waColl1 = $waColl | where-object {$_.IsAdministrationWebApplication -eq $FALSE}
write-host "WebApplication; Site Collection; List Title; List URL; EmailAlias"

foreach ($wa in $waColl1)
{

$sites = $wa.Sites

foreach ($obj in $sites)

{

$spSite = new-object Microsoft.SharePoint.SPSite($obj.URL)

$colWebsites = $spSite.AllWebs

foreach ($web in $colWebsites)
{

 $colLists = $web.Lists
 
 foreach ($list in $colLists)
 {

 if ( $list.EmailAlias -ne $null )
 {

 write-host  $wa.Name, ";", $obj.URL, ";", $list.Title , ";", $list.DefaultViewUrl, ";",  $list.EmailAlias

 }

 }

}

}

}

write-host "Finished."