Best day of the week to send emails

Have you wondered which is the best day of the week to send email marketing emails?
I recently tested the best day of the week and used open and click rate as the metric.

 Sunday, Saturday followed by Tuesday has the best open rate.

However Saturday also had one of the worst click through rates, suggesting to me people opened the email but did not click through. Sunday has the second largest click through rate and the largest open rate so must be the clear winner in this test.


Considerations..
Every week is different, 
A pay day may change behaviour
weather can have an impact


I believe school holidays made a difference to the above test as I sell a travel related service and this week of testing was one week before a half term holiday. I will retest again and I expect I will see different results on a different week.