I'm sure it will surprise you to learn that Ticketmaster is run by dicks. I just got some Depeche Mode spam from them after buying Bloc Party tickets last week. You can be sure that when I made that purchase, I didn't intend to give them permission to spam me. Here's the privacy notice that was attached to their message.

To Unsubscribe:

As a Ticketmaster user, you agree that Ticketmaster may contact you by email or other means and use and disclose the information you submit, as described in the Ticketmaster Privacy Policy.

If you would like to opt-out of receiving a particular type of email at this email address then please visit My Account and indicate your preferences. Please note that you may still receive emails from those who provide events (e.g., venues, teams, artists, promoters and leagues) to whom Ticketmaster provides your email address as described in the Ticketmaster Privacy Policy.

Please do not reply to this email. Replies to this email will NOT be responded to or read. If you have any questions or comments, contact us by email or postal mail: Ticketmaster-Optout Request, 4445 Corporation, Virginia Beach, VA 23462.

So you don't have an option to avoid getting these marketing emails when you buy tickets online. You can opt out after you begin receiving them, but this is just a formality: it won't actually stop them from selling your email address to whoever they'd like. And you can't register your displeasure with this policy without tracking down their email address or mailing a letter.

This type of bullshit should be illegal. Thank goodness I used a spamgourmet address.