metamail now misbehaving

[Steve Kleene <skdeb@syrano.acb.uc.edu>]

I run Wheezy with fvwm (window manager).  I prefer to use the command line
when possible, and for mail I have bsd-mailx with sendmail.  To read e-mails
sent as HTML or base64, I use metamail (which was last distributed with Etch,
I think), as follows:

  1. I save the e-mail to a file "mailfile".
  2. I call "metamail mailfile".
  3. Metamail silently extracts the HTML and saves it as, let's say, /tmp/Mu6MRTf.
  4. It calls "/usr/bin/iceweasel /tmp/MD7U6wY", which then displays the HTML.

Coincindent with my upgrade to firefox-esr 52, metamail no longer quite
works.  If no firefox window is up, it does succeed.  But if (as usual) a
firefox window already exists, it opens a new firefox tab with the error
"Firefox can't find the file at /tmp/Mu6MRTf".  And there is in fact no such
tmp file.

If I call "metamail -w mailfile", it offers to create /tmp/Mu6MRTf.  If I
approve that, I can then call "firefox-esr /tmp/Mu6MRTf" and see the HTML.  I
checked my backups, and updating firefox-esr caused no changes to
/etc/mailcap, ~/.mailcap, or the various redirects and alternatives for
firefox/iceweasel.

I'd be interested in any ideas on how to get this working again.  At the same
time, I expect that I will be advised give up on metamail.  I think
heirloom-mailx might be closest to what I already have.  To install that,
would I need to uninstall bsd-mailx first?  Can I assume that sendmail (and
sendmail.cf, etc.) will be left undisturbed?  I gather that mailutils and
mutt are other options.  I think mutt brings up its own window, and I'd
prefer to just use the command line for all the plain text e-mails I get.  On
the other hand, a better way to add attachments would be nice.  Currently I
do a lot of manual labor with the headers for those.

Thanks.