Mail gateway does a double DNS lookup and adds local domain name

[captainproton]

I am using 6.4-4 and after looking at my dns lookup logs I see an oddity I can't figure out.

For example, if my server is example.com and an external server (smtp.someserver.com) connects my server does a look up for smtp.someserver.com.example.com. Obviously this is returned as NXDOMAIN. Then my mail server does another lookup for smtp.someserver.com and gets the correct result.

Is that normal? Perhaps I'm missing something in the configuration.

EDIT: I should have mentioned I'm using Pihole for my internal DNS.

 

[captainproton]

Actually you can ignore this. For some inexplicable reason things have returned to normal.