Symantec Blacklist

HI all, sorry for my poor english!

I try to send mail to one domain protected by symantec, their IT told me that, one single address is blacklisted (only one user in my organization, other users can send at the same recipient)

Using the tool at this page: http://ipremoval.sms.symantec.com/lookup/ i had verified by myself the address, is not listed but marked as "neutral"

How can i request delisting for single user "user@company.com" and not for all "@company.com" or IP/Subnet?

More details i prefer to share via PVT message if needed.

Thanks