Incoming email feature stopped working after migrating to SharePoint 2010

Environment: SharePoint 2010 

Issue:

After migrating to SharePoint 2010 from SharePoint 2007, the incoming email stopped working and not anymore able to accept any invitation and showing on the Calendar web part. No specific event in Application log or SharePoint log file. After a couple of hour’s investigation, we figured it out the following steps to get it work.

Solution:

Please use the following steps as mentioned below…

1- Go to Calendar list

2- On the Ribbon, select List from the tab and click List Settings

3- Under Communication, click Incoming e-mail settings (see attached screenshot below)

4- In "Incoming E-mail" section, select "Allow this list to receive e-mail?" to “No” and save it.

5- Go back to same Incoming e-mail setting screen, select "Yes" this time and save it.

Then I sent an invitation from Outlook and wola - it worked fine and showed my invitation on Calendar this time. It looks like this setting was not saved properly during the migration even though apparently, everything looks ok and configured correctly.

Note: I will recommend creating a Powershell script batch file to open all sites calendar list and fix it as mentioned above i.e. turning off and on the specific property and avoid manually updating each site's calendar. It would be a big hassle if you have hundreds of sites created.