There's no HARM in you putting entries there. But nmh doesn't read that
file either.
Which raises the question - what is getting into the path so when Laura
adds entries to /etc/mailcap, things start working for her?
That's ... a good question.
First, it's not that I don't believe Laura. But ... I have some questions
about this. Like, exactly WHAT MIME types could you not view until you
added them? Were they text types? I ask because there are simply NOT
that many text types. There actually aren't that many MIME types in
general, and I'm wondering what ones you couldn't view and how long ago
you had to add them.
Secondly ... I knew this had come up before. Here's the earlier
message where this came up:
https://lists.nongnu.org/archive/html/nmh-workers/2015-03/msg00009.html
The short answer is FOR DEBIAN ONLY, the distribution of nmh was at the
time configured in mhn.defaults to use a program called "run-mailcap",
and I guess that uses the mailcap file. This had a poor interaction
with some types and nmh 1.6, but Alexander Zangerl (who is the Debian
nmh maintainer) said he was going to improve that, so I don't know what
the situation is under 1.7. Ralph suggested that there weren't any
Debian-specific changes in that regard, but you'd need to look at the
mhn.defaults file on your system to see the details.
--Ken