There are a lot of http links to mail.wiki[pm]edia.org, where mailman and pipermail are located.
I use the HTTPS Everywhere, and it was trying to force https instead of http, and reporting "Connection refused" errors.
One solution is to add an exclusion to the ruleset. eww
Another solution is to add https support.
Version: unspecified
Severity: enhancement
URL: https://lists.wikimedia.org/