We have been running Operating System: SUSE Linux Enterprise Server 11 SP3 - 64 Bit

Zimbra Version: Zimbra Collaboration Server 7.1 – Network Edition with Version 7.1.4_GA_2555

We need an immediate solution in our Zimbra Server to have OPT OUT Option in the mail recipients who are sending mail to External recipients. If the External recipient uses the OPT OUT Option Zimbra Server needs to restrict sending any mail to that specific External reciupient who has OPTED OUT.

Please help me how to configure this. Please also let me know if you require any more details.