we are building a service wherein anybody can add our domain to recipients ids to enable tracking...and security as to who is viewing the mail.
for eg. actual TO: harish@yahoo.com
new TO: harish@yahoo.com.ourDOMAIN.COM

the mail server has to catch anythin@anysubdomain.ourDOMAIN.com, and forward it to process@ourDOMAIN.com

we have been trying to tweak our server's dns to do this, but it repeatedly only works if we create subdomains like "yahoo.com"... we want it to catch any subdomain.

any help is appreciated.