[BlueOnyx:22518] Smarthost on port 587

[Colin Jack]

I have run into a problem and having struggled all morning have now decided to ask for help! 😊

We use an external smarthost which requires us to use the submission port and to  authenticate.
I set this up several months ago and it has been working fine until yesterday. Nothing has been changed on the server as far as we are aware.
We also have the sendmail.mc set to read-only as suggested by Michael

We are now getting 'relay denied' when sendmail sends automatically but it all works fine if I use a manual clear-out of the queue!

The support guys on the smarthost looked at the logs and said the problem was that we are connecting on port 25 ... but when we send manually it says port 587.

Example:

Nov 21 10:22:52 server1 sendmail[15795]: STARTTLS=client, relay=smtp.antispam.com., version=TLSv1/SSLv3, verify=OK, cipher=ECDHE-RSA-AES256-GCM-SHA384, bits=256/256 Nov 21 10:22:53 server1 sendmail[15795]: wALAMTqa015738: to=<colin at recipient.co.uk>, ctladdr=<sender at fast-mail.net> (750/500), delay=00:00:21, xdelay=00:00:02, mailer=relay, pri=130955, relay=smtp.antispam.com. [46.165.217.000], dsn=4.3.0, stat=Deferred: 451 relay not permitted!

But if I trigger manually it all goes through  ... sendmail -v -q

Running /var/spool/mqueue/wALAMwR0015813 (sequence 1 of 3) <colin at recipient.co.uk>... Connecting to smtp.antispam.com. port 587 via relay...
220 mx.antispam.com ESMTP Exim 142373 Wed, 21 Nov 2018 11:25:41 +0100
>>> EHLO server.fast-mail.net
250-mx.antispam.com Hello server.fast-mail.net [208.69.249.000] 250-SIZE 250-8BITMIME 250-DSN 250-AUTH PLAIN LOGIN 250-STARTTLS
250 HELP
>>> STARTTLS
220 TLS go ahead
>>> EHLO server.fast-mail.net
250-mx.antispam.com Hello server.fast-mail.net [208.69.249.000] 250-SIZE 250-8BITMIME 250-DSN 250-AUTH PLAIN LOGIN
250 HELP
>>> AUTH PLAIN 
>>> ZmFzdG1haWxAZmFzdC1tYWlsLm5ldABmYXN0bWFpbEBmYXN0LW1haWwubmV0AHBpZ3M4
>>> bGFkZGVy
235 Authentication succeeded
>>> MAIL From:<sender at fast-mail.net> SIZE=11548
250 OK
>>> RCPT To:<colin at recipient.co.uk>
250 Accepted
>>> DATA
354 Enter message, ending with "." on a line by itself
>>> .
250 OK id=1gPPhZ-0003qq-FP
<colin at recipient.co.uk>... Sent (OK id=1gPPhZ-0003qq-FP)

In my sendmail.mc:

define(`SMART_HOST', `smtp.antispam.com')
define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
FEATURE(`authinfo',`hash /etc/mail/auth/authinfo')dnl

Anybody able to help?

Thanks

Colin