It is email marketers’ jobs to provide readers with an enticing insight into an email’s content, whilst giving the reader an impression as to what the email is about. The subject line acts as a ‘window’ to the email and is arguably the single most important part, to determine whether the e-mail is to, or not to be opened, which is used by 100% of businesses (Ellis-Chadwick and Doherty, 2012) – with the need to have a consistent link between the subject line and email content.
via How to write email subject lines: What to do and what not to do | Stef G’s blog.