=item to_addr - who the email will be sent to (in addition to any bcc on the template)
+=item context_height - number of context stack levels to match against
+(0 or null matches against full stack, 1 only matches lowest level context, 2 matches lowest two levels, etc.)
+
=back
=head1 METHODS
|| $self->ut_number('min_level')
|| $self->ut_foreign_key('msgnum', 'msg_template', 'msgnum')
|| $self->ut_textn('to_addr')
+ || $self->ut_numbern('context_height')
;
return $error if $error;