Email Affiliated Contacts button for use with Salesforce NPSP

Email Affiliated Contacts

/**************************************************
/  Button: Email Affiliated Contacts              /
/  Author: Matt Horine                            /
/  Client: Step Up to Serve                       /
/  Date: 28 January 2015                          /
/                                                 /
/  Description: Button on Affiliated Contacts     /
/  related list to allow selection and email of   /
/  affiliated contacts from the Account Page in   /
/  the same way the Send an Email button allows   /
/  selection of contacts.                         /
**************************************************/  

// Notes and To Do
// To Do: Add button to full list view
// Note: Shows in Account activity history but not contact

{!REQUIRESCRIPT("/soap/ajax/19.0/connection.js")} 

// Get current url
var url = parent.location.href; 
// Get the current Account Id
var acctId = "{!Account.Id}";
// Get the set of Affiliated Contacts that have been selected
var records = {!GETRECORDIDS($ObjectType.npe5__Affiliation__c)}; 
// Create string of Ids for use in the SOQL Query ('X','Y','Z')
var ids = '';
for (var i=0; i<records.length; i++) {
  ids = ids + "'" + records[i] + "'";
  if (i<records.length-1) {
    ids = ids + ',';
  }
}

// Create array to hold the list of emails
var emailList = [];

// If no records selected, alert user
if (records[0] == null) {
	alert("Please select at least one Affiliated Contact to email."); 
} 
else { 
  // Create and run SOQL Query
  var queryResult = sforce.connection.query("SELECT Id, npe5__Contact__c, npe5__Contact__r.Email from npe5__Affiliation__c where Id in (" + ids + ")"); 

  // Place results in array variable
  var emailArray = queryResult.getArray("records"); 

  // Place email for each result in the email list array
  for (var j=0; j<emailArray.length; j++) {
    var cont = emailArray[j].npe5__Contact__r.Email;
    emailList.push(cont);
  }
  
  // Create URL for the send an email page. p24 is the Additional To
  // field.  p4 is the CC field, and p5 is the BCC field.
  parent.location.href = '/_ui/core/email/author/EmailAuthor?p3_lkid=' + acctId + '&retURL=%2F' + acctId + '&p24=' + emailList;
}

Thank you for this! I made some changes - available here if anyone wants.