Problems with muttrc.5:
Ambiguous or invalid backslash. This doesn't cause groff a problem.
but it confuses doclifter and may confuse older troff implementations.
Unknown or invalid macro. That is, one that does not fit in the
macro set that the man page seems to be using. This is a serious
error; it often means part of your text is being lost or rendered
incorrectly.
Use local definitions of .EX/.EE or .DS/.DE to avoid low-level troff
requests in the page body. There are plans to add these to groff man;
in the interim, this patch adds a compatible definition to your page.