Why shouldn't I use an OpenDNS or UltraDNS DNS servers for my Email Security Gateway's DNS lookups?

Solution #00006325

Scope:

All Email Security Gateways.

Answer:
OpenDNS and UltraDNS mangles our TXT record look-ups and converts them into A records, which breaks the look-up process.

Link to this page:

https://campus.barracuda.com/solution/501600000013Q11AAE