[GLLUG] Checking mail server configuration specifically for IPv4

John Winters john at sinodun.org.uk
Sat May 30 15:23:48 UTC 2020

Dear all,

I've been having a recent problem with one of my mail servers and one 
particular e-mail provider not liking its reverse DNS lookup result for 

I tend to use check-auth at verifier.port25.com to diagnose these things 
but I've hit a problem.  Both my mail server and theirs are fully IPv6 
enabled, and all is good in IPv6.

Does anyone know a way of forcing a similar check to use IPv4?  The 
e-mail provider with whom I'm having difficulty publishes only IPv4 MX 


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