Fix Incoming Emails Not Working Issue in SharePoint Migration

Problem:
After a Database attach method of SharePoint migration from SharePoint 2007 to SharePoint 2010, all incoming E-mail enabled libraries stopped working! They no longer receive E-mails!!  Here is the root cause and fix for SharePoint incoming email stopped working issue.

Root Cause:
This is because, SharePoint stores incoming E-mail configurations on its Farm Configuration Database (usually SharePoint_Config) and during database attachment method of migration, We didn't (and we can't) migrate the configuration database. So, incoming email settings on SharePoint 2010 not working.

Solution:
One quick solution is simply Flip the value of  "Allow this list to receive e-mail?"

1. Just go to List Settings
2. Under Communication, click on "Incoming e-mail settings" link
3. Select "Allow this list to receive e-mail?" to "No" and click on "Save"
4. Now, go back to the Incoming e-mail settings again and choose ""Allow this list to receive e-mail?" to "Yes" and then save your changes.

 We can also automate the above activities with PowerShell.

Wait, There is an elegant solution yet:
However there is an another efficient way by: Calling RefreshEmailEnabledObjects() method of SPSite object to refresh all Incoming Email settings! (or use: stsadm -o refreshdms command). Here is the PowerShell script:

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue
#Get All Site Collections of the given web application
$SiteCollections = Get-SPWebApplication "http://sharepoint.crescent.com" | Get-SPSite -Limit All 
 #Iterate through Each site collection
 foreach ($site in $SiteCollections)
 {
  #Refresh Incoming Email settings
  $site.RefreshEmailEnabledObjects()
  #Write Ouput message
  Write-Host "Processed: $($site.rootweb.url)"
  #Dispose the Site object
    $site.Dispose() 
    }