Effective email marketing campaigns are designed for all devices on which users can read their emails -- desktop, tablet, and smartphone. Email campaigns that are designed for mobile devices are especially important -- a quality known as "responsive design." In fact, 73% of companies today prioritize mobile device optimization when creating email marketing campaigns.
When it comes to deciding how to craft that perfect subject line, there appears to be really only one area to avoid: the subject line of 60 to 70 characters. Marketers refer to this as the “dead zone” of subject length. According to research by Adestra, which tracked over 900 million emails for its report, there is no increase in either open rate or clickthroughs at this 60-to-70 character length of subject line.