It's sometimes grey. One example I can give is Expedia, which provides me with a monthly 'Your [Month] Statement is Ready'-type of thing, even though I've maybe used the service once in my life to buy airplane tickets. You can't unsubscribe since it's not 'marketing' and e-mailing support didn't help either. Yet, it's marketing, because they offer promotional links ("earn free yadda yadda") and has Citi advertising below it.

Another one is 'Oh, wow, you've been getting some profile views!' that LinkedIn and other like to do. That's indirect promotion of their services. Couched as a reminder.

Today, after not logging into Facebook for a while, received an e-mail that someone commented on their profiles. Another of the same.

It can be argued that these is all a form of promotion, but this would take a less-business-friendly political climate to accomplish, if you ask me.