Subject lines: what's the story?
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Marcia Yudkin's Secrets of Mouthwatering Marketing Copy report focuses on the right way to present offers to prospects and customers.
The purpose of your marketing emails is to produce a desired reaction from the reader. This reaction can take numerous forms. Perhaps a click to your website leading to a purchase or download. Or simply a greater awareness of your business.
But whatever reaction you strive for, you won't get it if the recipient never reads the email.
So what determines whether an email gets more than a passing look?
People use a number of criteria to decide how to treat each email that appears in their inbox, but right up there near the top of the list (if not actually on the summit) is the simple subject line.
What you put in this subject line has a huge impact on the decision to read (or not) the email. Indeed, improvements to your subject lines are probably the best short-term way to make a meaningful difference to your bottom line email marketing results.
Why does the subject line have so much impact?
People browsing their inbox see very little information on each email. But two bits of information they do see are the so-called "from" and "subject line" headers. Different email software and services may call them different things and display them in different ways, but it's basically the information on the email's sender and subject (see screenshot below).

It's no surprise then that studies regularly show that these two headers are key to determining whether an email gets looked at or not.
From a marketing viewpoint, the "subject" line is more interesting than the "from" line. The latter is important, but you don't have a lot of creative flexibility here. (Some, but not a lot.) The subject line is both important and highly variable: you can write pretty much anything you want in there. So writing good subject lines becomes a more complex task.
But what makes a good subject line? What works best for getting the attention and interest of the reader? What boosts responses to your emails?
Fortunately, those questions are the subject of numerous articles online, and you can find a list in the "links" section of the main subject lines page.
Before you dive into those articles, though, a word or two to guide you in the task.
1. Despite what I said above, there are some limits on what you can write in a subject line.
There are, for example, legal restrictions on what you can and cannot put in a commercial email. In the USA, "...the subject line cannot mislead the recipient about the contents or subject matter of the message."
Other restrictions come from the field of deliverability: certain words and phrases in your subject line may cause the email to be flagged as spam.
2. There is no universally applicable "silver bullet" subject line. Experience shows that different types of marketing emails require different subject line approaches. For example, the subject line that works best for a sales email promoting a simple offer might produce terrible results if used for a content-rich information email newsletter.
3. Recipients do not read the subject line in isolation. Their reaction to the subject is mitigated by everything else they know about the email and particular the sender. If the reader already knows and trusts the sender, for example, then the subject line is released from the task of establishing that trust. You can write more freely than if the recipient is unfamiliar with the sender's identity.
4. Although subject lines and emails have their own idiosyncrasies, there's no reason why you can't draw on copywriting expertise and insights generated elsewhere (such as in paid search or direct marketing).
5. Every list of email addresses has its own unique character and the best subject line for one list and email will not be the best for another. That's why the best approach is to...
- Read up on (subject line) copywriting and review your own expertise and experience
- Draw out the important principles and guidelines
- Apply them to your subject lines to produce a set of likely "winners" for each new email
- Test these subject lines and use the results to add to your understanding of what works for your readers and emails
- Rework your subjects accordingly.
- Rinse and repeat.
Subject line effectiveness changes through time (you can rarely repeat the same subject line with the same audience and get the same good results indefinitely), so you need to keep testing and adapting, testing and adapting.
Good luck!
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