Hmmm, thanks, that adds a bit more to consider, but doesn't explain the problem. I guess after I used my hotmail acount to test the subscribtion form on my homepage it could be that it won't send out a confirmation message to the same addres after I've unsubscribed it and then re-subscribed it manually. But... the other hotmail address I tried it with hasn't been used for anything other than the manual subscription, so... ???
I'm positive I'm following the steps correctly too. I've customised the confirmaion message which should be sent out to those addresses I subsribe manually myself, and I hit the button to do the job - there's not really much space to go wrong. Which I guess is why I'm so confused.
I could perhaps try the same with a few addresses which aren't hotmail, but in the case that Hotmail does pose a problem it would mean a large section of the people I wish to subscribe just aren't going to get the confirmation message, since unsurprisingly many (perhaps most) are Hotmail addresses.
Any other thoughts are very welcome!