Linked-In has the spammiest email protocol out of any service I have ever used. Even after signing-in there is no one-click-to-unsubscribe button (they split it into about 12 scattered categories), and they create new categories periodically and opt you in to them. This is downright deceitful. Pro tip: change your email to one that you never use. It literally came down to doing this or deleting my Linked-in account--unfathomable to me. Also: no more f@#$!ng emails at 4 in the morning. This seems like a jackpot CAN-SPAM class action suit.
@easternmonk: That's the thing -- I did mark them as spam in GMail. I assumed it would block future emails from Linked-in but not the case. ... Somehow they continued to come in.
@sehugg: That too! I complained about their this on Facebook and I had friends (yes, plural) who had deleted their account because of the spam and yet were still receiving it. Unbelievable