Firstly, what a great idea - there are plenty of people out there who don't know what they are doing. However, (caution rant...)
There are people out there that do know what they are doing. When something that was working breaks without any changes on their part they can waste hours investigating why their DNS server is now failing. (this was compunded by the fact that the secondaries servers where failing as the primary has been unavailable for too long....)
Your on call support staff where unaware of this feature and "port 53 is blocked for technical reasons - can't do anything about it." was the response - thankfully your twitter people are better informed
this wasn't announced to users email (at least I didn't receive a mail shot...)
To compound matters - your various systems don't accept compliant SMTP addresses to allow mail forwarding. (relay.plus.net will reject user@[ip.address] as there is no A or MX record - that's what the "[" "]" is for - its an ipaddress use it! mailbox redirect setup will not accept it either - so plus.net mail was sending to a black hole - so couldn;t even signup to use these forums! If you believe my router was compromised let me know, its akin to a mechanic thinking your car wiper motor is faulty and removing it to prevent damage but not telling you... everything looks fine for ages, then it rains...
I'm sorry that the changes our Networks Team have had a negative effect on you. Unfortunately the changes that were made were never going to be beneficial for all, but it helped and protected a large amount of customers. If there is something we can do to help, please do let us know.