Email marketing is an effective and cost-efficient way to boost sales. But which subject lines have the biggest impact? Tim Watson reveals why some of the received wisdom about subject lines may be misleading
Subject lines in email marketing are absolutely crucial - so it's not surprising there's so much advice out there. In testing I've found the right subject line can double click rates, though a 25% gain is more typical and still welcome.
However, with all the advice there's a lot of talk of best practice - some of which is actually completely wrong. So what are the myths about subject lines, and why should we ignore them?
Myth 1: Don't use CAPITALs in subject lines
This stems from the idea that using capitals is like shouting, and it's rude to shout. In addition, it's thought capitals are harder to read. I've reviewed thousands of subject lines and I only found one in which the whole subject line was upper case. The use of a few capitalised words, however, is relatively common.
Using capitals does help subject lines to stand out and give emphasis to key words. About once a month, Miss Selfridge uses a subject line that begins: "PETITES EXCLUSIVE".
The rest of the subject line depends on their offers that month. As well as standing out, the regular use of this capitalisation trains customers to know, recognise and expect it.
Myth 2: Personalisation makes emails look like spam
The concern here is not that the email gets filtered as spam, but that it comes across as tacky and tarnishes a brand. Marketing opinions on this are divided. But in tests the use of a first name often gives an increased response rate.
The most common personalisation is to include the first name at the start of the subject line, such as: "Tim, Weekend Super Saver 15% off".
However, the best subject line personalisation goes beyond just the name and tailors the whole subject line to a person or segment.
Real world examples include Disney, which includes names in about one in four subject lines. Using the same approach every time creates boredom, so the Disney approach of varying the subject line style makes more sense. If you do see a split test uplift with use of first name, do re-test regularly to check its effectiveness is not lost.
Myth 3: Don't use spam trigger words like "Free" in the subject line
This is probably one of the most persistent old wives' tales when it comes to subject lines. The received wisdom is that the use of "free" gets you filtered to junk.
Many years ago there was some truth in this, as at that time email was largely filtered based on content. However, the biggest spam filtering factor now is reputation, which itself is heavily based on spam complaints. Content is now only likely to get you filtered to junk if your reputation is weak.
So go ahead and use 'free' and other sales trigger words, and even put free in upper case too. Keep an eye on the inbox placement - if you see a problem, cut back on the sales words and resolve your underlying reputation issue.
Myth 4: Judge subject lines by the open rate
If a subject line creates lots of opens but few clicks and conversions, just how good was it really? For most commercial mailings open rates are a weak measure of marketing objective. Click, post-click and conversion measures are better metrics, even when it comes to deciding on subject lines.
It's not uncommon to see a lower open rate subject line generate higher click rates. This happens when the lower open rate subject line is a better qualifier. Fewer people may open; however, those that did were the right people and were more likely to click, leading to high click rates overall.
Myth 5: Keep subject lines short
I've nothing against short subject lines. The problem is that they often lose meaning and clarity. If the subject line is too short, the reader doesn't know what the email is about and it loses its effectiveness.
Take these two short lines from Ryanair: “Book Today” and “£5 Seat Sale”. The second one is better as it says something about the email content. In this example the £5 offer was limited to midnight on the following Monday (48 hours from when the email was sent). Given that urgency is a strong driver, it might have been worth using a longer subject line and including the cut-off date. Had the offer been around particular destinations, then adding those would also better qualify the openers.
Determine your message and then say it succinctly. Concentrate on getting your message communicated, not the number of characters.
Myth 6: The only point of a subject line is to get an open
Many customers read your subject line but don't open your email. The subject line message still has impact even when an open doesn't follow. It leaves an impression with the consumer.
Your brand values, product range and more can be communicated through the subject line, even to non-openers.
Myth 7: I know what works
We are not always the best judges of subject lines that work. Customers are the best judges, and split testing is an easy and effective way of understanding what they think.
Split testing subject lines is one of the easiest optimisation wins. The win is not just to get an uplift on the current campaign, but analysis of subject line differences helps guide future campaigns.
Subject lines are attention grabbers that need to resonate with the reader. The best subject lines are written when there is a clear sense as to exactly who the reader is and what they want, when you express what's in it for them and ensure it's well aligned to the content of the email.
Tim Watson has more than eight years’ experience in B2B and B2C email marketing, helping blue chip brands with successful email marketing. He is an elected member of the UK DMA Email Council and active participant of the Best Practice and Legal hub.