From purslow1 at ca.inter.net  Fri Sep 25 07:59:48 2026
From: purslow1 at ca.inter.net (Philip Webb)
Date: Fri, 25 Sep 2026 03:59:48 -0400
Subject: authentication problem when sending mail via Mutt
Message-ID: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>

Recently, I suddenly encountered "SASL authentication failed",
when trying to send an e-mail using Mutt 2.3.2 on Gentoo Linux ;
earlier that day, I had sent several e-mails successfully
& had made no changes in my hardware or software.
I have used Mutt without serious problems since c 1998 .

At the end of? .muttrc? I have

 ? set ssl_starttls=yes
 ? set ssl_force_tls=yes
 ? set smtp_url="smtp://<me at myispaddress>:25"
 ? set smtp_pass="<my password>"

My e-mail ISP denied that they had made any changes at their end,
but the conversation was brief & I find it hard to believe :
perhaps it was a small change which their man hadn't heard about.

I've installed Thunderbird, which has no problem connecting,
& have sent several e-mails successfully that way.
However, Mutt suits my needs better & I'ld like to go on using it.

Can anyone suggest anything I might try in order to restore access ?

-- 

========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatcadotinterdotnet


From rory at campbell-lange.net  Fri Sep 25 08:54:24 2026
From: rory at campbell-lange.net (Rory Campbell-Lange)
Date: Fri, 25 Sep 2026 09:54:24 +0100
Subject: authentication problem when sending mail via Mutt
In-Reply-To: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>
References: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>
Message-ID: <arY2wCT2zzXVpIdp@campbell-lange.net>

On 25/09/26, Philip Webb (purslow1 at ca.inter.net) wrote:
> Recently, I suddenly encountered "SASL authentication failed",
> when trying to send an e-mail using Mutt 2.3.2 on Gentoo Linux ;
...
> Can anyone suggest anything I might try in order to restore access ?

I use exim locally rather than direct SMTP sending from mutt, so can't help
directly.

However, perhaps the `swaks` command line tool could be helpful in nailing down
the issue?

The Debian repo entry is:

Description-en: SMTP command-line test tool
 swaks (Swiss Army Knife SMTP) is a command-line tool written in Perl
 for testing SMTP setups; it supports STARTTLS and SMTP AUTH (PLAIN,
 LOGIN, CRAM-MD5, SPA, and DIGEST-MD5). swaks allows one to stop the
 SMTP dialog at any stage, e.g to check RCPT TO: without actually
 sending a mail.
 .
 If you are spending too much time iterating "telnet foo.example 25"
 swaks is for you.

From kevin at 8t8.us  Fri Sep 25 10:54:38 2026
From: kevin at 8t8.us (Kevin J. McCarthy)
Date: Fri, 25 Sep 2026 18:54:38 +0800
Subject: authentication problem when sending mail via Mutt
In-Reply-To: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>
References: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>
Message-ID: <20260925105438.fNOvlsPH@8t8.us>

On Fri, Sep 25, 2026 at 03:59:48AM -0400, Philip Webb wrote:
>Recently, I suddenly encountered "SASL authentication failed",
>when trying to send an e-mail using Mutt 2.3.2 on Gentoo Linux ;
>earlier that day, I had sent several e-mails successfully
>& had made no changes in my hardware or software.
>I have used Mutt without serious problems since c 1998 .
>
>At the end of? .muttrc? I have
>
>? set ssl_starttls=yes
>? set ssl_force_tls=yes
>? set smtp_url="smtp://<me at myispaddress>:25"

Double check the port number.  This would typically be :587 when using 
STARTTLS.  25 is only used between SMTP servers for relaying email 
nowadays.

-- 
Kevin J. McCarthy
GPG Fingerprint: 8975 A9B3 3AA3 7910 385C  5308 ADEF 7684 8031 6BDA
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From mutt at tim.thechases.com  Fri Sep 25 16:49:32 2026
From: mutt at tim.thechases.com (Tim Chase)
Date: Fri, 25 Sep 2026 11:49:32 -0500
Subject: authentication problem when sending mail via Mutt
In-Reply-To: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>
References: <7d3923bf-9828-4ba3-b596-16c5c7045757@ca.inter.net>
Message-ID: <aramHH41ywMICgl9@thechases.com>

On 2026-09-25 03:59, Philip Webb wrote:
> My e-mail ISP denied that they had made any changes at their end,
> but the conversation was brief & I find it hard to believe:

I agree that something feels suspect here.

I'm not sure whether your residential-ISP is the same as your
email-provider, but

- if they're *not* the same, and you checked that one didn't make a
change, the other might have

- if they *are* the same, some team (whether the ISP-service or
email-service) might have started filtering without notifying the
team with whom you spoke.

Additionally many residential ISPs will block all outbound port 25
(and some will block *in*bound port 25), so it might be blocked at the
network level.

> set ssl_starttls=yes
> set ssl_force_tls=yes
> set smtp_url="smtp://<me at myispaddress>:25"
> set smtp_pass="<my password>"

And with STARTTLS, you might be better off using port 587
(STARTTLS) or 465 (implicit TLS) because of the aforementioned
possible-port-25-blocking.

> I've installed Thunderbird, which has no problem connecting,

Did it auto-determine the port for SMTP or did you specify :25?

Alternatively, Thunderbird might be using a different list of allowable
root certificates compared to the trust-store that Mutt is using, so you
might be connecting yet getting the error because of an untrusted
trust-anchor.

Similarly, it would be worth knowing which authentication methods the
server supports (PLAIN, DIGEST-MD5, GSSAPI, CRAM-MD5) and check your
mutt {pop,imap,smtp}_authenticators settings to see which ones are
allowed (if unset, mutt tries them in order from most-to-least secure
http://www.mutt.org/doc/manual/#smtp-authenticators ). Thunderbird might
be choosing a diferent authenticator.

-tkc
--