Careful when using OpenDNS. Examples:
smtp5:/# host -t mx sdsdsdsdsdsdsdsdsgmail.com 208.67.220.220
sdsdsdsdsdsdsdsdsgmail.com does not exist at resolver2.opendns.com, try again
smtp5:/# host -t a sdsdsdsdsdsdsdsdsgmail.com 208.67.220.220
sdsdsdsdsdsdsdsdsgmail.com A 67.215.65.132
!!! sdsdsdsdsdsdsdsdsgmail.com A record has zero ttl
smtp5:/# host -t a sdsdsdsdsdsdsdsdsgmail.com
sdsdsdsdsdsdsdsdsgmail.com does not exist (Authoritative answer)
If you're checking for an A-record you'll always get an answer with OpenDNS.
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Regards,
Martin Nicholas.