@c snarfed from "mu_scm.c":130
@deffn {Scheme procedure} mu-register-format rest
Registers desired mailutils formats. Any number of arguments can be given.
Each argument must be one of the following strings:

@multitable @columnfractions 0.3 0.6
@headitem Argument @tab Meaning
@item @samp{mbox}  @tab Regular UNIX mbox format
@item @samp{mh}    @tab @acronym{MH} mailbox format
@item @samp{maildir} @tab @i{Maildir} mailbox format
@item @samp{pop}   @tab @acronym{POP} mailbox format
@item @samp{imap}  @tab @acronym{IMAP} mailbox format
@item @samp{sendmail} @tab @i{sendmail} mailer format
@item @samp{smtp}  @tab @acronym{SMTP} mailer format
@end multitable

If called without arguments, the function registers all available formats

@end deffn

@c snarfed from "mu_scm.c":163
@deffn {Scheme procedure} mu-strerror err
Return the error message corresponding to @var{err}, which must be
an integer value.

@end deffn