This week, ExactTarget released their 2005 Response Rate Study that summarized open, click-through and unsubscribe rates.
The results of their study?
Even though Tuesdays are the highest volume of sending emails day, Friday is the day with the highest OPEN RATES...even though SUNDAY is the best day for CLICK-THROUGH RATES (CTR).
First, does this matter?
Their reasoning is that there is less competition for your emails on Fridays...thus, the highest open rate of any day... but, if you read into the study further, you'll find Friday was the highest open rate day by only .6% with Thursdays being the #2 day for email open rates. This is not a statistically significant difference to make any conclusions.