To find out what times during the day are best for email opens and click-throughs, email marketing software provider GetResponse analyzed 21 million messages sent from US accounts during the first quarter of 2012.

The study found that 23.63% of all email opens occur within the first hour after delivery. Within the second hour after delivery, the results drop by half.

The top engagement times for email are as follows: in the mornings, 8 AM to 9 AM both for opens and click-throughs; and in the afternoons, 3 PM to 8 PM for opens, and 3 PM and 4 PM for click-throughs.

Time zones are also a consideration: Email marketers should keep in mind local times and work routines around the world, and stagger their mailings accordingly, keeping in mind the best times of day for engagement, according to GetResponse.