Subj : smtp-auth required?
To   : Digital Man
From : Nelgin
Date : Tue Mar 21 2023 14:32:28

  Re: smtp-auth required?
  By: Digital Man to Nelgin on Tue Mar 21 2023 11:06:19

 > That error message is not from the Synchronet mail server.

That's odd.

# telnet endofthelinebbs.com 25
Trying 192.138.210.158...
Connected to endofthelinebbs.com.
Escape character is '^]'.
220 endofthelinebbs.com Synchronet SMTP Server 3.20a-Linux Ready
ehlo pbx.endofthelinebbs.com
250-endofthelinebbs.com
250-AUTH PLAIN LOGIN CRAM-MD5
250-SEND
250-SOML
250-SAML
250-8BITMIME
250-STARTTLS
250-SIZE 20971520
250 OK
mail from: <pbx@endofthelinebbs.com>
250 OK
rcpt to: <sysop@endofthelinebbs.com>
250 OK
data
354 send the mail data, end with <CRLF>.<CRLF>
Testing
..
554 Mail deliveries from endofthelinebbs.com must use SMTP-AUTH

If I telnet to my BBS and try to deliver directly, I get the message. I don't know where else it could be coming from?

.