<div dir="ltr"><br><div>What is your sender SMTP sending as for HELO ?</div><div><br></div><div>"fully qualified" means the receiver is expecting a full host and domain name.</div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Aug 5, 2021 at 2:50 PM Grand Rapids Linux Users Group <<a href="mailto:grlug@grlug.org">grlug@grlug.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Running a django container, sending email via postfix on the host, ...<br>
<br>
Unfortunately, some receiving MTAs are getting blocked:<br>
<br>
2021-08-05T14:14:11.006284-04:00 majordomo postfix/smtp[178627]:<br>
6C9C473D1: to=<<a href="mailto:lvl@omnitec.net" target="_blank">lvl@omnitec.net</a>>,<br>
relay=<a href="http://mx2.omnitec.net" rel="noreferrer" target="_blank">mx2.omnitec.net</a>[206.197.251.201]:25, delay=0.57,<br>
delays=0.01/0.01/0.31/0.24, dsn=5.0.0, status=bounced (host<br>
<a href="http://mx2.omnitec.net" rel="noreferrer" target="_blank">mx2.omnitec.net</a>[206.197.251.201] said: 504 <majordomo>: Helo command<br>
rejected: need fully-qualified hostname (in reply to RCPT TO command))<br>
<br>
However, the HELO IS valid:<br>
<br>
$ telnet mx2 25<br>
Trying 206.197.251.201...<br>
Connected to mx2.<br>
Escape character is '^]'.<br>
220 <a href="http://mx1.omnitec.net" rel="noreferrer" target="_blank">mx1.omnitec.net</a> ESMTP<br>
<br>
Appreciate any thoughts, ..<br>
<br>
        Thanks!<br>
-- <br>
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</blockquote></div>