how to add "sendemail" button in gridView of customized entity in crm

There is one customized entity named as "Add to Campaign" . Since there is no default "Email" button in sub-grid , so i placed one customized button and provided javascript to open Email form , and the Email form opens good. But now the problem is , cant able to get selected records "Email field" in "Send to field" in Email Form. so how to get selected record email to be displaced in "Email Form"

Solution

Open the email form with parameters:

Xrm.Utility.openEntityForm("email", null, param);

var param = {}; // passed as parameters to the new email form
if(Xrm.Page.getAttribute("-- LogicalNameOfField --") // make sure that the field has a value
    param["-- LogicalNameOfFieldInNewEmail --"] = Xrm.Page.getAttribute("-- LogicalNameOfField --"); // passes a field value to the new form
// This passes a lookup field as a parameter to the new form
if(Xrm.Page.getAttribute("-- LogicalNameOfLookup --").getValue() != null) { // make sure that the lookup field is not empty or we will have a problem trying to access [0].id and [0].name
    param["-- LogicalNameofLooupFieldInEmail --"] = Xrm.Page.getAttribute("-- LogicalNameOfLookup --").getValue()[0].id;
param["-- LogicalNameOfLookup --" + "name" (eg. "accountname")] = Xrm.Page.getAttribute("-- LogicalNameOfLookup --"].getValue()[0].name;
Xrm.Utility.OpenEntityForm("LogicalEntityName", null, param); // open the form and pass parameters

Take note of how the lookup field is passed as a parameters:

2 parameters are passed for each lookup field
The GUID as the name of the lookup field (account if account if the name of the lookup field in the new email)
The name of the lookup in the source entity as a special parameter (accountname)
Note: there is no field called "accountname", but there is a field called "account" in this hypothetical entity