Forum: Ruby How do I unsubscribe from the mailing list?

I have sent "unsubscribe" in the body to ruby-talk-ctl@ruby-lang.org
many times but it keeps sending back:

your mail has no effective commands
please read the following help and send requests to
<ruby-talk-ctl@ruby-lang.org>

"Eduardo B." <lists@ruby-forum.com> wrote:
> I have sent "unsubscribe" in the body to ruby-talk-ctl@ruby-lang.org
> many times but it keeps sending back:
>
> your mail has no effective commands
> please read the following help and send requests to
> <ruby-talk-ctl@ruby-lang.org>

Can you make sure your email client is sending a text/plain message
_without_ base64 encoding?

Hmmm, I will try to do that.  Might be a problem with Outlook.com...

Took a few tries but it worked in plain text mode using the old hotmail. 
Thanks!