What time of day do you email?

As a columnist for All About eMail, I have access to the Email Campaign Archive powered by their parent company, Target Marketing Magazine. Every month something like 18,000 new promotions are added to the file.  I’m amazed at the volume of email sent between 10 and 11 a.m. Monday-Friday, month in and month out.  There isn’t change.

I looked at March, 2011, stats (the most recent).  There were 18,265 emails logged into the database.  1,906 were received between 10 am and 11 am.  While that doesn’t sound impressive, consider this:

Since about 88% of promotion email is sent Monday-Friday, that suggests about 1,677 were sent during that one hour of the business day during the month of March.  There were 23 business days in March, so an average of nearly 73 email promotions were within that one hour each business day – or an email about every 49 seconds.

Have you tested other times of the day, and specifically, 10 am vs earlier or later in the day?  And what you can say about your experience?