elm email gets through, exmh email doesn't

[Mark Phillips <mark@ist.flinders.edu.au>]

Hi,

I've just set up my machine so it can email the rest of the world, at
least I thought I had.

I can now successfully send email to "mark@ist.flinders.edu.au" using
elm, but when I try and send a similar message using exmh, it complains
that:

  mark at ist.flinders.edu.au: loses; [USER] 550 relaying to
<mark@ist.flinders.edu.au> prohibited by administrator
post: 1 addressee undeliverable
send: message not delivered to anyone


What on earth does this mean and why isn't it working???

Thanks,

Mark.

_/~~~~~~~~\___/~~~~~~\____________________________________________________
____/~~\_____/~~\__/~~\__________________________Mark_Phillips____________
____/~~\_____/~~\________________________________mark@ist.flinders.edu.au_
____/~~\HE___/~~\__/~~\APTAIN_____________________________________________
____/~~\______/~~~~~~\____________________________________________________
__________________________________________________________________________
        "They told me I was gullible ... and I believed them!"