mailman refuses to let me subscribe

[Alan Chandler <alan@chandlerfamily.org.uk>]

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I have set up mailman on my local server box.

I have set up a list, and then attempted to subscribe to it.  It refuses to 
let me, saying " Your subscription is not allowed because the email address 
you gave is insecure. "

What does that mean? why?
- -- 
Alan Chandler
alan@chandlerfamily.org.uk
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