The Comcast.Net email sever seems to have recently decided that emails from the NMCCSkiClub Egroup are SPAM and deletes them without putting the emails in a Spam folder. Thanks Comcast.
First off, here's the Xfinity FAQ on how to change email settings.
Here are some work-arounds:
In a browser log onto to your Xfinity account.
Click on Check Email.
In the Email API click Settings (the gear icon on the right)
Now there a a couple of ways.
1-In Settings click Filter Rules
Then add a Rule that has firstname.lastname@example.org in the Sender.
Add Action: Choose the action Move the Email, choose Inbox.
Then your local client, Thunderbird, Outlook, etc. can pick up the emails as usual from your Comcast Inbox. You could use another destination Folder if you wanted to also.
See screen grab below.
2-In Settings go to Advanced Settings
Click Keep Emails Marked As Spam at the bottom. This puts the club emails into the Spam folder which is probably not what you want if you're actually grabbing the emails locally using Outlook or Thunderbird, etc. But maybe you consider NMCCSCEGROUP as Spam so this works for you then.
However, this has the disadvantage that you may now get other spam that comcast.net was deleting too in the Spam folder.
3-In Settings go to Advanced Settings
UNClick Enable Spam Filtering. This turns off all of comcast's Spam filtering. You'll get NMCCSCEgroup emails in the INBOX folder that you weren't seeing but everything else it was deleting too.
One of these should fix the prob.
Screenshot of Xfinity->Check Mail->Settings->Filter Rules