Retrieve multiple email addresses from data table and insert as input into email service

I'm not so clear what you want to do as the code you provided seems to be missing some comments and brackets.

But creating a string like "email1;email2;email3;" for the SendMessage service you can just do

var tableLength = result.rows.length;
var emailReceivers = ""; // empty mail string
for (var x = 0; x < tableLength; x++) {
 var row = result.rows[x];
 emailReceivers += row.Email + ";"; // append "email;" to receivers
}

if (emailReceivers.length > 0)
 emailReceivers = emailReceivers.slice(0, -1); // remove last ;

Hope this helps.