private String getMailToAddressesAsString() {
    StringBuilder mailToList = new StringBuilder();
    for (final String mailToAddress : mailToAddresses) {
      mailToList.append(mailToAddress);
      mailToList.append(", ");
    }
    return mailToList.toString();
  }
@return All the registered email id as string
geode-core/src/main/java/org/apache/geode/admin/jmx/internal/MailManager.java