A recent study by Email Service Provider (ESP) MailerMailer titled Email Marketing Metrics Report, measured more than 300 million e-mail messages sent by 3,200 of its e-mail clients across 21 different industries between July 1 and December 31, 2007.
It shows that seventy-four percent of the consumers who open an e-mail message do so within the first 24 hours, and in 48 hours that number rises to 83%.
The highlights of the report are:
•    Mondays, Tuesdays and Weekends are best days to send.
•    Wednesdays and Friday’s are the days your email is least likely to be read.
•    Tuesday mailings typically get the highest click rates.
•    Shorter Subject Lines (less than 35 characters) significantly outperform longer subject lines (greater than 35 characters) by both open rate and click through rate (CTR.)
•    Subject line personalization is the single best place to add personalization if you want to improve open rate and CTR.
•    Shoot for having either 5-10 links or over 20 links for best performance. Try to avoid having 6-19 links within your emails.
•    Text messages show a very slight advantage in CTR over HTML, but the percentage is negligible.
The report also found that e-mail open rates continue to decline at a higher rate than previous years. The overall unique open rate for e-mails sent by MailerMailer customers in the last six months of 2007 declined more than 2%; from 16.11% at the beginning of 2007, to 13.98% during the last six months of 2007. According to the report, this period’s drop was “possibly due to the proliferation of e-mails being viewed on handheld devices.”
However, click rates were not affected as strongly as open rates. Click rates for the last half of 2007 reached 2.9%, coming down only slightly from 3.18% in the first half of 2007.
Banking and finance saw the highest open rates, rising from 6.52% in the first half of the year to 6.98% in the second half.