smtpmail and ~/.authinfo

[Eli Zaretskii]

I switched today to using ~/.authinfo with smtpmail in Emacs 24 for
the first time, and immediately hit a snag: sending mail failed with
an error message from the SMTP server claiming that my login
credentials were incorrect.

It turned out that ~/.authinfo _must_ have Unix EOLs, or else sending
mail with smtpmail not work.  This happens because auth-source-search
is called from smtpmail inside a form that let-binds
coding-system-for-read to `binary'.  That binding is there for reasons
that have nothing to do with auth-source-search, and a cursory search
finds no similar bindings in other users of auth-source-search.

It should be easy to fix this, but I need to know what can be in Netrc
files to do this correctly.  Can these files include non-ASCII
characters, or do all fields in these files have to be strict 7-bit
ASCII?  If non-ASCII characters are allowed, then are there any
limitations on the charsets that can be used in Netrc files, or can
they be anything at all in any valid encoding?  Also, is there any
need to do something special with non-ASCII characters (if they are
allowed) when communicating with the SMTP server, like encode them in
some particular way?

Given the answers to these questions, fixing the above problem should
be as simple as adding a few lines to smtpmail-via-smtp.

TIA