HELO (email config problem) - Printable Version

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HELO (email config problem) - sdgathman - 08-14-2019

The forum emails provide only the classic HELO <fqdn> for authentication.  This is fine, and RFC correct, although only a few knowledgeable email admins actually check it (or configure it correctly).  Big Email providers like to insist on PTR (which is not RFC correct - that is what HELO is for).  There is also a valid IP4 PTR record at for  But there is no IPv6 PTR record: not found: 3(NXDOMAIN)

Sending to Big Email providers that insist on PTR via IPv6 may fail.

The HELO for the forums emails is HELO, and the DNS for lists only an A record for  This is fine for sending emails to IP4 servers. has entered the 21st century, and also sends emails via IPv6!  Great job!  Unfortunately, the IPv6 address is not listed in DNS, so the HELO authentication fails in that case.  (The FQDN in HELO must resolve to the connect ip.)  Since no other authentication is provided, my email server rejects the emails by default.  (I, of course, have overridden this by adding a local SPF record for

To simplest solution is to simply add the missing AAAA record to DNS:  IN AAAA 2a02:af8:fab0:800:31:193:136:207

It would also be a good idea to add the PTR ("reverse DNS") for the IPv6 address to keep Big Email happy.

In addition, I could not find a button to resend the activation email.  My account had to be manually activated by an admin on IRC.