Your email won't get read if it's caught by a SPAM filter. Most people know some of the words that trigger filters, like "FREE" and "CIALIS," but few people realize that there are actually about 100 of these words. In addition to the above, MailChimp has identified three words that generally get through SPAM filters but which for some reason, people don't like when it comes to opening emails: Help, Percent off (% off), and Reminder.
With this in mind, here are two subject lines from MailChimp's research. The first received open rate of less than 1%, the second an open rate of over 90%:
Subject: Final reminder for complimentary entry to attend the West Freelands BCI Cluster Conference 2006
Subject: Your April Website Stats