Marketing emails need to be personalized to the reader and filled with interesting graphics. Few people want to read emails that are addressed "Dear Sir/Madam" -- as opposed to their first or last name -- and even fewer people want to read an email that simply gives them a wall of text. Visuals help your recipients quickly understand what the point of the email is.
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.