The longer the length (in characters) of a B2C email subject line, the higher its open, click, and click-to-open rates, finds Adestra in a July 2012 study of 932 million emails from more than 40,000 campaigns across 6 sectors, sent over a 6-month period. The results show that B2C emails have a below-average click-to-open rate (CTOR) for subject lines between 20 and 60 characters in length, but after that pick up steam, hitting their peak at 150 characters in length. These emails have a CTOR 94.7% above the average (and click and open rates 276.4% and 93.2% above-average, respectively). B2B emails show a similar trend, though not quite as clear cut. Emails with subject line length of 20 characters performed above-average for all 3 metrics, though the rates generally dipped after that until recovering from 90 characters in length and up. The peak for open rate was 20 characters (24.6% above-average), while the peak for click rate was for 140 characters (82.7% above-average) and for CTOR was also 140 characters (72% above-average). Read the rest at MarketingCharts.