Awesome, thanks all! From an end user perspective that would be a perfectly acceptable outcome, the warning just serves to confuse people. Appreciate the help!

Let me know if you want full logs, but here is the segment with more info.

So looking through the logs it appears that it is trying a lookup against our domain, in addition to the key server we have configured.

Ah OK I'm following now, I had took that as maybe another lookup at that time was failing. The keyserver that we have configured is hkps://keys.openpgp.org. Is there any misconfiguration here with that setting?

OK, so this warning should just be ignored then?

Apologies for the delay here, but the particular user claimed it was no longer an issue and it fell off my radar. However I now have a new individual with the same problem.