If you have a list, you can drive monster gains via basic A/B testing of components.

- Time of day sends make huge differences, early AMs test well for us despite article's counter point.

- Highest open rates are Sunday but Tuesday we see highest level of transactions.

- Including company name in your email can increase opens and clicks substantially.

etc etc - so much good data on this topic - particuarlly the first link:

http://www.email-marketing-reports.com/tactics/best-time-to-...

http://conversionvoodoo.com/blog/2010/07/personalizing-your-...

http://www.mailermailer.com/resources/metrics/index.rwp