We use a mailman moderated list four our church group. We have around 200 or so users.
Recently, we have experienced an issue with messages not being sent to the list when they contain links to web pages. We receive an acknowledgement that the list has received the message and it appears in the archive, but it is not received by anyone.
If we remove the link, the messages go out with no problems.
I'm afraid that my shared hosting account won't let me view log files, so I can't see if an error is being generated.
I am unaware of any option that validates or checks web links within a message.
Any thoughts would be appreciated.