email delays from Google

Tue Jul 30 23:02:56 UTC 2019

We have been experiencing delays / failures receiving email from domains 
hosted by Google and *only* domains hosted by Google.

This is happening to customers for whom we host the authoritative DNS 
servers.   For some reason, Google is not able to look up the MX and/or 
A record *sometimes* from our servers.

Customers are getting an error like this:
--BEGIN
DNS Error: 49391460 DNS type ‘mx’ lookup of <domain hosted with us> 
responded with code NOERROR 49391460 DNS type ‘aaaa’ lookup of 
mail.internetpro.net <http://mail.internetpro.net>. responded with code 
SERVFAIL 49391460 DNS type ‘a’ lookup of mail.internetpro.net 
<http://mail.internetpro.net>. responded with code SERVFAIL

--END

In the above case, Google is saying they can't find our mail server.  
There is no AAAA record, so that part is normal.

However, we have other customers who are hosting their own mail servers 
or are using relay services such as Trend Micro who are also having a 
similar issue.  The only thing these customers have in common is our DNS 
and the fact that Google is trying to send email to them.

I can query Google's public servers at 8.8.8.8 and 8.8.4.4 and they 
always give the correct answers, but it seems that internally, Google is 
unable to make these lookups.   Reaching out to their support agents 
online, the agents confirm that the correct entries are in place and 
that *some* of Google's servers can't do the resolution resulting in 
sporadic email delivery.  They suggest that we reach out to the DNS 
provider to find out why (Grrr)

We've also had reports from customers that the failures seem to be 
location oriented with western US emails being held up and eastern US 
emails coming through.  I can't independently confirm that, though.

A full 100% of the email delivery issues have been Google hosted 
domains.   It seems that every other ISP can do the lookups just fine, 
but getting in touch with someone at Google who can troubleshoot this is 
impossible for a small ISP like us.

If anyone can point me to somone at Google who could help me out, I'd be 
very thankful.

Trey Nolen