GMail SMTP: no authenticators available?

[Baron Fujimoto]

On Wed, 20 Jan 2021, Will Yardley wrote:

> On Wed, Jan 20, 2021 at 04:22:04PM -1000, Baron Fujimoto wrote:
>>
>> The following in my muttrc was used successfully util this problem began:
>>
>> set smtp_url = smtp://user@example.org@smtp.gmail.com
>
> Do you have smtp_authenticators (unset by default) set?
>
> set smtp_url = "smtps://luser@example.com@smtp.gmail.com"
> set smtp_authenticators = 'gssapi:login'
>
> Are you using an "app password"? Typically, you'll need to (at least I
> did)
> https://support.google.com/mail/answer/185833?hl=en-GB
>
> If not, you may want to switch to one. If so, you may want to make sure
> it's still active, and check to see if your organization changed any
> policies that might be causing the issue, whether that's disabling
> certain protocols, or enforcing MFA.
>
> FWIW, when I was using gsuite with Mutt (for work), I would typically
> have to auth once for IMAP and once for SMTP.
>
> Good idea trying alternate ports, but you may also want to doublecheck
> that your provider is not blocking or hijacking SMTP (and see what you
> get using telnet and / or openssl s_client to connect to smtp.gmail.com
> directly). Kevin's suggestion should also help show any issues along
> those lines.
>
> w

Sorry, I should have added that I do not have smtp_authenticators set, so it should be trying all available as the default.

I also tried using an app password, which also works for IMAP, but not for SMTP, same as before. The "No available authenticators" error occurs before I am even prompted for a password when trying to send.

When I experiment with "openssl s_client", I can only connect to port 465, but I don't see any obvious problems there either. I'm not quite sure how to satisfiy GMail's AUTH requirements via interactive SMTP commands. (I tried AUTH LOGIN, with base64 encoded responses to Username: and Password: but get a Bad Credentials response using either my app password or original password).

Below is a excerpt of "mutt -d 2" output. Based on what I see there, it doesn't appear that them SMTP is being hijacked. But apparently not even LOGIN or PLAIN AUTH mechanisms appear to be available to mutt?

---------
Sending message...
Looking up smtp.gmail.com...
Connecting to smtp.gmail.com...
ssl_load_certificates: loading trusted certificates
ssl_socket_open: Error loading trusted certificates
ssl_verify_callback: checking cert chain entry /OU=GlobalSign Root CA - R2/O=GlobalSign/CN=GlobalSign (preverify: 1 skipmode: 0)
ssl_verify_callback: checking cert chain entry /C=US/O=Google Trust Services/CN=GTS CA 1O1 (preverify: 1 skipmode: 0)
ssl_verify_callback: checking cert chain entry /C=US/ST=California/L=Mountain View/O=Google LLC/CN=smtp.gmail.com (preverify: 1 skipmode: 0)
ssl_verify_callback: hostname check passed
TLSv1.3 connection using TLSv1.3 (TLS_AES_256_GCM_SHA384)
Connected to smtp.gmail.com:465 on fd=8
8< 220 smtp.gmail.com ESMTP s76sm6536334pfc.35 - gsmtp
8> EHLO MacBook-Pro.local
8< 250-smtp.gmail.com at your service, [192.160.100.100]
8< 250-SIZE 35882577
8< 250-8BITMIME
8< 250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
8< 250-ENHANCEDSTATUSCODES
8< 250-PIPELINING
8< 250-CHUNKING
8< 250 SMTPUTF8
SASL local ip: 172.19.100.162;59923, remote ip:74.125.20.109;465
External SSF: 256
External authentication name: user at example.org
SASL: No worthy mechs found
smtp_auth_sasl: LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH unavailable
No authenticators available
mutt_free_body: unlinking /var/folders/2y/zz20bmnx69zbk82vm71syr5w0000gp/T//mutt-MacBook-Pro-502-51733-18433303713026120095.
Mail not sent.
---------
(email address and client IP address redacted)