This is likely to be because you have blocked Hullomail from accessing your contacts.

Hullomail will add the contact if you allow access via the following:

1. Open your iPhone Settings
2. Locate 'Hullomail' app settings
3. Enable access permissions to 'Contacts'
4. Then close and re-open the Hullomail app

If this is not possible please send us an email at contactus@thumbtel.com