Keep it short to about 20-35 characters. Why? Too short and it won't be descriptive enough and too long and the subject line in it's entirety won't preview in most of today's email platforms and that's pretty useless if... See what I mean?
Keep out the mumbo jumbo. Replace £ with GBP, $ with USD and try to avoid special characters like exclamation marks! Special characters can trigger spam and sometimes they just don't render properly for the recipient. Generally, the higher your sender score, the less you have to worry about your subject line setting off alarm bells for spam. You can check your sender score (using an IP lookup) here: https://www.senderscore.org/
FREE SPECIAL DISCOUNT IN OUR SALE! NOW! Numerous other factors in a subject line can add to an increased spam-rating too, especially; CAPITILISATION, words like 'free', 'discount', 'offer' and the list goes on. Test your subject line with this free tool: http://www.localnews.biz/subjectline/validatesubjectline.asp . Although a little over-sensitive at times, it's very handy to have at your disposal.
The best time to send emails is at... There is no such thing as a best universal time to broadcast your email, but there is a best time for when you should be sending your emails, but there's only one way to find out: split test different days and different times. Make sure the tests are fair by using identical emails, subject lines and equal segments of data. You may find Monday produces a better open rate but Tuesday produces a better conversion rate.
Two subject lines in your emails... Many email platforms now preview the first few characters of your email (most notably: Gmail) after the subject line before the reader has opened the email. Choose from the following tools to preview subject lines in a variety of platforms: Inbox Inspector from Mail Chimp and litmus, the latter also having a very handing spam-checking tool.
Make it relevant! I'll never forget the email I got with the subject line "Want #accessory#for your Lexus IS200?". I didn't own a Lexus and the company knew what car I had on file. Always remember to make as much use of the data that is available to you, put yourself in the receiver's shoes...would you want to be sold accessories for a car you don't own?
Hey Fred, we've got news for you. Personalisation can work well in subject lines, but make sure you have the correct data. If you're using a script to automatically populate this data, it's not going to look good if they didn't include their name when they signed up, or maybe they spelt their name wrong - which will end up being your fault, the customer's always right. Always have a backup plan in this case, for incomplete data.
Test your subject line before you broadcast. Have you ever considered testing your subject line on another channel? Get a handful of proposed subject lines and test them in PPC ads and see which one get's the higher CTR, a few pounds spent on some brief PPC activity could mean big money when it doubles your open rate!
Let the data do the talking. There are always people in your business that won't listen to your recommendations on subject lines. If you've got the data that shows how your database reacts, use it to your advantage and don't go along with other people's gut feelings.
Cross my heart. No one likes a liar, give them a clear and quick insight into what's in your email. The hard work has only just begun once you've hooked your recipients with your subject line and if you just go with the quick win "Massive discount off your next order" you'll probably get a good open rate but you can guarantee that your unsubscribe rates will go up and your click-through rates, go down when they find out it's only 5% off orders over £100. Try not to over-promise with your subject lines and under-deliver with your content, it's always better for a recipient not to open the email and stay a subscriber, rather than open it and unsubscribe.
