opt-in check box


I am starting to look at e-Newsletter and can not see a specific way to add an opt-in box when a new user is created.

What I am trying to achieve is that when a user creates a new blog on multi-site they are given the option to opt-in at the time of creation.

Whilst in UK law there is such a thing as soft-opt-in when making a sale, it states to comply "the recipient was given a simple means of refusing (free of charge except for the cost of transmission) the use of their contact details for marketing purposes when those details were initially collected and, if they did not refuse the use of those details, at the time of each subsequent communication."

Which basically means, that we have to provide a tick box that they can 'un-tick' at the time the account was created.

Does this feature exist in this plug-in somewhere that I didn't find?.

It wouldn't be beyond me to create a little additional user data to slot in like 'TOC' plug-in if it isn't but I don't want to do work that I can avoid.