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@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
--
