Hi All,

 pls explain bellow statement how to build this ?

location.replace('_ui/core/email/author/EmailAuthor?p2_lkid={!Commercial_Agreement__c.My_Cutom_To_EmailField__c}&rtype=003&p3_lkid={!Commercial_Agreement__c.Id}
&rtype=003&p24={!Commercial_Agreement__c.My_Custom_AdditionalToEmail__c}&retURL=/{!Commercial_Agreement__c.Id}&template_id=00XA0000000Dv41')

and what are the p2_lkid, rtype,  p3_lkid and where we can see this variables and wher these values will send (where it will check)?