[MlMt] Rule to bounce messages with no subject

[Verdon Vaillancourt]

On 5 Oct 2018, at 3:11, Jan Erik Moström wrote:

> On 4 Oct 2018, at 16:12, Verdon Vaillancourt wrote:
>
>> As a side-rant… what kind of mail client allows you to send a 
>> message with a blank subject! Oh. Ya. Gmail.
>
> And mailmate ... and most other clients I know of

At least mailmate throws up a warning about missing subject before it 
will send :-)