OT - Help with resulting error message

[Steve Campbell]

Jethro R Binks wrote:
> On Wed, 3 Jun 2009, Steve Campbell wrote:
>
>   
>> One of our users is trying to email users at a particular domain and is
>> receiving the following error message back from them:
>>
>> (reason: 550 5.7.1 rejected content, black listed twitter.com by
>> multi.surbl.org #762 #895 (l51Ehj043192426600))
>>
>> I asked if he was posting through twitter, and he said he was not. I 
>> checked SURBL and our IPs are not listed. So I'm confused(as always) by 
>> what this is telling me. He does have a reference to his twitter stuff 
>> in his signature. Do any of the SURBL lists really block content?
>>
>> A good explanation would be helpful. Thanks much
>>     
>
>   http://lists.surbl.org/pipermail/discuss/2009-June/
>
>
> .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
> Jethro R Binks
> Computing Officer, IT Services, University Of Strathclyde, Glasgow, UK
>   

So after reading the entire thread, am I right in assuming that one of 
multi.surbl.org's DNS servers is having it's cache poisoned, and thusly 
the receiving mail server that is rejecting  our user's email based on 
the poisoned return from SURBL?

Our DNS servers are returning NXDOMAIN for twitter.com.multi.surbl.org.

Very interesting reading though.

Thanks Jethro.