On Wed, Sep 30, 2026 at 17:48:07 -0500, David Wright wrote: > I no longer use exim to queue outgoing external emails, as attachments > are transferred so quickly that mutt isn't held up for any significant > period of time. So my emails like this one get sent directly to a > submission port at my email hosting service. > > I assume mutt (MUA) gets its HELO from /etc/hosts.
I've never used mutt in that way, so I don't know where it gets its configuration. The online documentation for mutt's SMTP doesn't say much at all: <http://mutt.org/doc/manual/#smtp> 5. SMTP Support Besides supporting traditional mail delivery through a sendmail-compatible program, Mutt supports delivery through SMTP if it was configured and built with --enable-smtp. If the configuration variable $smtp_url is set, Mutt will contact the given SMTP server to deliver messages; if it is unset, Mutt will use the program specified by $sendmail. For details on the URL syntax, please see Section 1.2, “URL Syntax”. The built-in SMTP support supports encryption (the smtps protocol using SSL or TLS) as well as SMTP authentication using SASL. The authentication mechanisms for SASL are specified in $smtp_authenticators defaulting to an empty list which makes Mutt try all available methods from most-secure to least-secure. That's literally the whole documentation. If you want to dig into this, you could trace an SMTP session with something like tcpdump, or look in the logs on a receiving SMTP machine to which you have access, or check the full headers on a message sent via mutt's SMTP, or ask on a mutt mailing list.
