Hello JNic,

You need to enclose the Collected Ids in a specific standard format.

With GETRECORDIDS you get Ids as a, b, c

But in dynamic query you need to have ids as ('a', 'b', 'c')

Following code might help you in understanding more clearly.

{!RequireScript("/soap/ajax/20.0/connection.js")}

var contactRecords= {!GETRECORDIDS($ObjectType.Contact)};

var csvContactIds = "";
//fetch csv format Ids
for(var rowNum in contactRecords){
    csvContactIds += "'"+ contactRecords[rowNum] + "',";
}

//remove last comma
csvContactIds = csvContactIds.slice(0, csvContactIds.length - 1);

//Enclose the ids in round brackets
if(csvContactIds.length > 1){
    csvContactIds = "(" + csvContactIds + ")";
}


var contactEmails = " ";

var ccEmails = "p4=salesforce@tionetworks.com&"; 

if (contactRecords.length ==0) {
    alert("Please select at least one Contact record.");
} 
else {
	
    var result = sforce.connection.query("select Name, Id, Email from Contact Where Id IN " +csvContactIds); 
    var records = result.getArray("records"); 
    
    var email = "";
    for (var i=0; i< records.length; i++) {
        email += records[i].Email + '\n'; 
    }
    contactEmails += email;
    alert("records:"+contactEmails); 
}

Please mark it as resolved if its what you were looking for, It might help other developers facing similar issue.