Email service provider (Yahoo) doesn't seem to be very reliable, some people get their links, some people don't, inactive accounts with 0 posts get deleted at the beginning of each month.
Accounts with more than 1 valid post doesn't get deleted due to inactivity.
An account is not needed to access links on K1 whether that changes in the future depends on how much of a money drain K1 is in the future.
No, it's unlikely that Email service will get any better, K1 sends out enough activation emails or thread subscription notifications daily that most free service providers delete K1's account. We're still getting new members daily so some people are getting the emails.
It is also unlikely K1 will move to a paid email service as most people run adblockers so K1's ad revenue has dropped so low it can't even cover internet fees anymore.
Kureha does not wish to implement ad banners or deploy anti-adblock mechanisms on the forum.