I believe that's how LinkedIn works, but it's also the case even when attempting to permanently delete your account. I finally managed to successfully delete my LinkedIn account around 8 months ago, but then recently I accidentally followed a link to a LinkedIn page on my work machine, and apparently there was still a cookie around, so LinkedIn was kind enough to reactivate my account without warning. And oh how the spam did flow.

To be extra careful, I think you need to unsubscribe from all email, deactivate your account, delete all LinkedIn cookies from all your machines, and you might as well kill linkedin.com in your hosts files.