Error while sending a mail from mutt

[Jim Davis]

On Wed, Mar 29, 2017 at 12:32 PM, AYAN KUMAR HALDER
<ayankumarh at gmail.com> wrote:
> Hi,
>
> I am trying to send a mail using mutt. I am getting the error as follows :-
>
> SMTP session failed: 501 5.5.4
>
> I understand the error meant that a valid mail transaction protocol
> was used with invalid arguments. Please let me know how do I debug
> this issue further.

Mutt usually invokes some other program to send mail -- on my
workstation, for instance, that other program is /usr/sbin/sendmail:

[jim at krebstar ~]$ mutt -v | grep '^SENDMAIL'
SENDMAIL="/usr/sbin/sendmail"

so to debug a similar problem on my workstation I'd first look to see
where sendmail (or whatever program your mutt installation uses) logs
its messages.

That used to be in /var/log/maillog or such; nowadays you might have
to run journalctl instead.

For example, if I try

mutt postmaster at example.com </dev/null

on my workstation, then

journalctl | grep sendmail

tells me

Mar 29 12:59:06 krebstar.arl.arizona.edu sendmail[27263]:
v2TJx61J027263: to=postmaster at example.com, ctladdr=jim (1000/1000),
delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30294,
relay=[127.0.0.1] [127.0.0.1], dsn=4.0.0, stat=Deferred: Connection
refused by [127.0.0.1]

which reminds me I don't actually have the sendmail service running.

-- 
Jim