Hi Joachim,
Please make sure the list is not set to subscriber only; it is an unreasonable burden to subscribe for people who just want to send you one question, and possibly have to contact dozends of different package authors, e.g. as a distribution packager.
+1 I have had that problem, too. Maintainers give contact details, but then I have to jump through hoops before I can actually contact them. I see why people want to protect themselves from spam, but this approach seems counter-productive to me.
(Who really thinks that using the subscriber-only setting of mailman as an anti-spam-measure is an abuse of the feature, and that mailman should offer a “non-subscribers get a bounce that allows them to approve the message themselves“ feature which would give the same spam protection but much less hassle for the users.)
The way to accomplish that is to configure the list as "moderated", and to set all list subscribers as "unmoderated". This makes postings from subscribers go right through, and everyone else's message are forwarded to the list moderator for approval. It's not quite the same as a challenge-response scheme that empowers casual posters to confirm their honest intentions (i.e. the correctness of their mail envelope address), but it's still a lot better than just dropping every mail from anyone who isn't subscribed. Take care, Peter