The MX record is not a requirement for mail delivery. RFC compliant mailers will fallback to the A record. Since the non-delivery issues seem to be intermittent for most people, I don’t think the missing MX record is really the root problem.

The DNS configuration for gerry.vanagon.com is definitely not up to modern standards (no SPF/DKIM as you note), but the server is also running Listserv 1.8d, which came out in 1999, so it’s just one of many things that are not up to modern standards.

In any case, the only person who can really diagnose this problem is the admin for the gerry.vanagon.com server. The mail server and mailing list software should both be generating log files with success/failures for all messages sent to the list, and you really need access to those logs to figure out what’s going on. I think troubleshooting this from only the client side is going to be almost impossible.

-ben

> On Jan 2, 2020, at 2:00 PM, Ryan Cresawn <jrcresawn@GMAIL.COM> wrote:
> 
> The absence of an MX record is an excellent observation Mike. Furthermore,
> no TXT record exists for gerry.vanagon.com. TXT records are used to store
> SPF and DKIM records that are used by other email service providers to
> determine the trustworthiness of gerry.vanagon.com. I am happy to help
> improve the DNS records for gerry.vanagon.com.
> 
> Ryan
> 
> On Thu, Jan 2, 2020 at 10:49 AM Michael A. Radtke <wa7zpu@5by9.net> wrote:
> 
>> Hello,
>> 
>> No one commented on my earlier post, so maybe no one is getting my
>> posts as well.
>> 
>> GERRY.VANAGON.COM does not appear to have a DNS MX record.  Since mail
>> is coming from GERRY.VANAGON.COM some email providers may simply delete
>> messages without valid MX records.
>> 
>> Or put another way, mail from GERRY.VANAGON.COM has a trust level of
>> 0.1 on a scale of 0-10 according to https://tools.verifyemailaddress.io.
>> 
>> Mike
>> 
>