Last Friday late night, I suddenly started getting a lot of bounced emails from the dgplug mailing list. Within a few minutes, I received more than a thousand emails. A quick look inside of the bounce emails showed the following error:

Unauthenticated email from yahoo.in is not accepted due to     domain's 550-5.7.1 DMARC policy.

Gmail was blocking one person’s email via our list (he sent that using Yahoo and from his iPhone client), and caused more than 1700 gmail users in our list in the nomail block unless they check for the mailman’s email and click to reenable their membership.

I panicked for a couple of minutes and then started manually clicking on the mailman2 UI for each user to unblock them. However, that was too many clicks. Suddenly I remembered the suggestion from Saptak about using JavaScript to do this kind of work. Even though I tried to learn JavaScript 4 times and failed happily, I thought a bit searching on Duckduckgo and search/replace within example code can help me out.

$checkboxes = document.querySelectorAll("[name$=nomail]");
for (var i=0; i<$checkboxes.length; i++)  {
      $checkboxes[i].checked = false;
}

The above small script helped me to uncheck 50 email addresses at a time, and I managed to unblock the email addresses without spending too many hours clicking.

I have also modified the mailing list DMARC settings as suggested. Now, have to wait and see if this happens again.