If you fool with php much, you can probably edit this line in the modules/Your_Account/index.php file Nuke 7.0+ un der the
function activate area

Code:

$db->sql_query("INSERT INTO ".$user_prefix."_users (user_id, username, user_email, user_password, user_avatar, user_avatar_type, user_regdate, user_lang) VALUES (NULL, '$row[username]', '$row[user_email]', '$row[user_password]', 'gallery/blank.gif', 3, '$row[user_regdate]', '$language')");

what that line does is insert values into the users table when the user activates himself with the activation link your site sends.
You would need to look at the users table to dtermine what field are there that you want to insert values for in that line.
I would think that something like this would add the value of ON to the Email notification field.

Code:

$db->sql_query("INSERT INTO ".$user_prefix."_users (user_id, username, user_email, user_password, user_avatar, user_avatar_type, user_regdate, user_lang, user_notify, user_notify_pm) VALUES (NULL, '$row[username]', '$row[user_email]', '$row[user_password]', 'gallery/blank.gif', 3, '$row[user_regdate]', '$language', 1, 1)");

I added user_notify, user_notify_pm and then added the values of 1 for each to that line. That MIGHT work.

EDIT: I just tested and it works. I doubt you want to turn on everything for the user though. I would just turn on the email notification stuff. If you turn on Newsletter you might have some users calling you a spammer :wink: