You will agonise over the content on the subject line for you next email marketing campaign. If you accept that the eleven points below are correct, then it should make things easier.
1/ There is more than one
Each Subject Line must to tuned to a section of your subscriber list. One size does not fit all that many.
2/ The Subject Line is not the most important reason subscribers choose to open an email
It is a major factor but subscribers are less likely to open an email if the previous one you sent had little relevance to them.
3/ It took too long to read
Forcing your subscribers to read a long explanation is an imposition. 50 characters is the maximum unless there is a need to go longer.
4/ Plan for the preview text
The material you cannot fit in the Subject Line can be included in the preview text box.
5/ Be honest
If you raise false hopes, expect yours to be dashed. Nothing makes a subscriber less likely to open the next email than the previous one deliberately misleading.
6/ Don't hide
Honesty includes including the circumstances that might put people off. If there is a limited number, then make this a positive factor: 'Urgent. Only 300 seats available.'
7/ Hit them with your best bit
You main offer is not a cherry on a cake, to be savoured at the end. Let the reader know immediately what you are offering.
8/ Numbers work
7 Ways to . . . whatever. Keep the number low though as more is not necessarily the merrier. Offering 37 ways to please your dog will be read as 20 minutes of the reader's life to be wasted. Further, an odd, but fairly low,number means that each one is there because it is interesting.
If the subject line identifies the recipient, and in the manner that they prefer, then it is more likely to be opened as it is a signal that you treat that person as an individual. This can be reinforced by the opening paragraph to the email: ‘As a buyer of [whatever] you might appreciate . . . Make them think you consider their needs. Also, appreciate is a word that confers discretion on the reader.
10/ Word according to time
Phraseology that will generate interest on a Thursday morning will be less effective on a Friday evening when the weekend beckons. You could, of course, change the sending time, but if your email marketing software shows that it is the most productive, tune your Subject Line to take this into consideration.
11/ What do you think this last point might be?
Not everybody likes to have to think, preferring bald statements. But many will be intrigued by a question that relates to them in some way. ‘Is staff turnover hurting your profits?’ is likely to trigger a response in most HR departments.
Subject Lines are a test but one which, if you go into it with an idea of what you want, and what you need to avoid, it is well worth that little bit of effort.