Whitelist email keeps being moved back to blacklist email

Whitelist email keeps being moved back to blacklist email

Hi there,
I cannot seem to keep 1 email address in the Whitelist Email list.

I have added the Domain into the Whitelist, then added the particular email address to the whitelist from the blacklist. However the email address keeps being moved back into the blacklist, no matter how any times i whitelist it.I get the appropriate notification from the system saying "blacklist email updated successfully"

Whitelisted Domain - groupy.co.nz   
Whitelisted Email - mailer@groupy.co.nz    - this is the email that keeps going to the Blacklist

Thanks