DNS format error

[Jim Pazarena]

I see in my logs "DNS format error from 205.178.190.53#53 resolving
excelwetsuits.com/MX for client 207.34.147.83#54521: invalid response"
The client is *my* mail server IP.

I am wondering is this error on MY side or their's ? It doesn't sound
like it.

If it's on their end.. how far should someone go to attempt to contact
them to correct the issue?

If it's on my end, I can't imagine what the issue may be.

Thanks.