This whole email for a track trend is kind of a slippery slope. Remember the "no purchase necessary" rule (err federal law) that comes with contests? People feel the same way about giving up an email address.
Giving up an email address (or text/sms, or IM, or twitter, or physical addy) is about permission... and long term interest. It is about a relationship. Just because I want to hear your music, doesn't mean that I give you permission to contact me.
The difference needs to be clearly stated upfront and permissions (and rejections) need to managed with integrity.
Labels: email marketing, fans, mp3s, permission