Splits a string of comma-separated emails, appending default domain.

def SplitEmailsAndAppendEmailDomain(self, address_list):
    """Splits a string of comma-separated emails, appending default domain."""
    result = []
    # Process email addresses, and build up a list.
    if isinstance(address_list, rdf_standard.DomainEmailAddress):
      address_list = [str(address_list)]
    elif isinstance(address_list, string_types):
      address_list = [address for address in address_list.split(",") if address]
    for address in address_list:
      result.append(self.AddEmailDomain(address))
    return result