Email Subject Lines

Mailchimp has a great piece - with some actual data to back up their findings - on best practices for writing subject lines. Since we cover subject line writing in class (and I suggest a few tips of my own, including the cheesy ones), this is a good set of guidelines for those of you wishing to dig a little bit deeper into subject line writing: What are some best practices in writing email subject lines? | MailChimp.com