|One of the most significant factors in determining response rates is how positive (words like great) or negative (words like bad) the words in the message are. Emails that were slightly to moderately positive OR slightly to moderately negative elicited between 5-15% more responses than emails that were completely neutral.|
We would advise against both excessive flattery and writing hostile, day-ruining screeds. Poisonously negative emails were less likely than even neutral emails to get a response, and extremely positive emails did little better.
|The sweet spot for email length is between 50-125 words, yielding response rates above 50%. While average emails from Jeb and Hillary clock in at 10 and 9 words respectively, unless you're running for President, sending emails that short mean you'll sacrifice about 30% of your responses. Response rates slowly declined from 125 word messages to 500 word messages, then fell faster after that. So if you need to send War and Peace, you might want to send it as an attachment!|
|Email marketing veterans know that testing subject lines is a critical step in designing an email campaign that will have a high open rate. Likewise, the length of your subject line impacts response rates, and the optimal length is shorter than we expected. Subject lines with only 3-4 words (excluding email conventions like Re: and Fwd:) received the most responses. Including some sort of subject line is critical: only 14% of messages without any subject line at all received a response.|
|Our most surprising finding was that the reading grade level of your emails has a dramatic impact on response rates. Emails written at a 3rd grade reading level were optimal, providing a 36% lift over emails written at a college reading level and a 17% higher response rate than emails written at a high school reading level.|
The main components of reading grade level scores are the number of syllables in your words and the number of words in your sentences. So try using shorter sentences and simpler words than you normally would. You can check your content's reading grade level in the Word Count tool in most word processors, or search for “Flesch Kincaid grade level" to find a multitude of online tools.