Sulu\Component\Contact\Model\ContactInterface::getMainAccount PHP Method

    public function getMainAccount();

 /**
  * Gets email address of a contact
  *
  * @param ContactInterface $contact
  * @param bool $useFallback
  *
  * @return string|null
  */
 public function getEmailAddressOfContact(ContactInterface $contact, $useFallback = true)
 {
     // take contacts main-email
     $contactMainEmail = $contact->getMainEmail();
     if ($contact && $contactMainEmail) {
         return $contactMainEmail;
     }
     // fallback take contact's main-account main-email
     $account = $contact->getMainAccount();
     if ($useFallback && $account) {
         return $this->getEmailAddressOfAccount($account);
     }
     return null;
 }