[Mailman-Users] illegible message in moderation approval queue

[Matt Morgan]

I have a message in a moderation queue. It's from a member (everyone is
moderated on this list) so I think it's not spam or other junk. But when I
click to review it, it's not legible. This is all I see in the message
excerpt:

IENvbnNkaXNsaXN0DQoNCrOqwMcgaVBob25lv6G8rSC6uLO/

I feel like I've seen other messages that look encoded/illegible in
moderation, though I don't have other examples right now. What can cause
this?

For what it's worth, the sender is a speaker of a language that uses a
different character set, so if that's possible cause, that might be the
reason here.

Thanks,
Matt