hotmail doesn't work

I have this problem aswell.
Hotmail users sometimes don't receive the confirmation email
AOL users never receive it

I have found no workaround yet, just asked the users to use another email domain in the disclaimer and activate the accounts manually when requested by email.
To activate the account manually, I change the group to 4 and change activate_string and activate_key to NULL then change the password to the hash of a default password.

depends of the default password you want to set

1- set the password you want to be the default to your account
2- use phpMyAdmin to get the hash in the database (password field in the pun_user database)
3- save the hash somewhere
4- reset your account password to what your usual password
5- when validating manually an account, replace the content of the password field by the hash you saved and provide the user with the default password you used to create the hash

It'll probably be something in the content of the headers that they are filtering upon, but their techinfo on their website is appalling, (what miniscule amount actually exists), so figuring out which bit is nigh on impossible without changing each bit piece by piece and trying again.