Subject lines

There has been a lot of discussion in various places recently about subject line length and how it affects email marketing. There have been multiple studies done on how the subject line affects opens and clicks. (Mailchimp, Alchemy Worx, Mailer Mailer, Adestra). The discussion has even spilled over into Ken Magill’s newsletter today.
I’ve had a couple people ask me my opinion on subject line over the years. My general response is that subject line length is not directly measured by spamfilters and so don’t fret about the length. It is true that consistently crafting poor subject lines can indirectly cause delivery problems. Send mail few people open and that will hurt your reputation over time.
I think Ken really said it best, though.

It isn’t the length that sells. It’s the words.

The subject line should be long enough to tell the recipient why they should open your mail.
The subject line should be short enough that there is some information the recipient has to get in the mail.
The subject line should accurately reflect the offer inside
The subject line can contain words like “FREE” and exclamation points.
The subject line shouldn’t contain so many exclamation points that the recipient decides the mail is spam and doesn’t open it.
The subject line should be short enough the recipient can read it in their mail client.
A great subject line can lift opens and clicks, but fussing about the exact length of the subject line is probably an overall waste of time.

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Standard Email Metrics

The EEC has been working on standardizing metrics used in email marketing. They have published a set of definitions for different terms many email marketers use. They published their Support the Adoption of Email Metrics (S.A.M.E) guide in June.
Under the new EEC definitions an open is measured when either a tracking pixel is displayed or a user clicks on any link in the email, including the unsubscribe link. Open rate is defined as the number of opens (either unique or total) divided by the number of accepted emails. Accepted emails equals the number of emails sent minus the number of emails rejected by the ISP for any reason.
The authors do caution, however, that even their measurements may under count the number of email subscribers that actually open or read an email. Some readers don’t load images or click on links but happily read and digest the content being sent. Others may not click on a link but actually visit a website or brick and mortar store to purchase something based on the email.
Overall, I think the definitions created by the S.A.M.E. group accurately reflect the things they want to measure within the limits of what is actually measurable. Their definitions won’t affect conversations in the short term, but are likely to drive change to standard terminology over the longer term. I do strongly encourage people to grab a copy of their document and see how their definitions compare with your current measurements.

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Reporting email disposition

Most regular readers know I think open and click through rates are actually proxy measurements. That is they measure things that correlate with reading and interacting with an email and can be used to estimate how much an email is wanted by the recipients.
The holy grail is, of course, having ISPs report back exact metrics on what a user did with an email. Did the user read it? Did it stay open on their screen a long time? Did the user just mark it read or throw it away? What happened to the message. Marketers would love this information.
It’s unlikely the ISPs will ever provide this information to marketers. Take away all the technical challenges, and there are some significant ones there are still social challenges to making this data available. Current user contracts protect the privacy of the user, local laws prohibit sharing this data. And, there is the vocal group of privacy advocates that will protest and raise a big stink.
I’m not sure why email is gets the special treatment of expecting the channel owners to provide detailed disposition data. In no other direct marketing venue is that information collected or provided. TV stations can’t tell advertisers whether or not someone watched a commercial, fast forwarded through it or got up to grab a beer from the fridge. The post office can’t tell direct mail marketers whether or not a recipient read the mail or just dumped it in the big recycling bin the post office provides for unwanted messages. Billboard owners can’t tell advertisers how many people read the billboard.
Since we can’t get exact read rates from ISPs, what do we do? We look at proxy numbers.
Read rate directly measures who opened the message. Open rate is a proxy. It’s who displayed images in the message.
Read rate can be measured only by people who have access to the user’s inbox. The ISPs can measure read rate because they have full access to the mailbox, but this requires the user to access the mailbox through webmail or IMAP. Some third party mailbox addons can measure it, but this requires the cooperation of the mailbox owner. If the mailbox owner doesn’t install the reporting tool, then the 3rd party doesn’t have access to the data. Only groups with access to the end users mailbox can measure this rate.
Open rate can be measured by people who have access to the server images are hosted. Senders and ESPs and 3rd parties can measure it if they provide unique image IDs or tracking pixels in their emails. Open tracking does require the cooperation of the recipient – they have to have images on. No images on, no open tracking. Ironically, ISPs cannot measure open rate, because they have no access to the image hosting servers.
Click rate can be measured by people who have access to the server that hosts the website. The same people who can measure opens can measure clicks. Some ISPs can measure clicks, Hotmail used to pass every URL through a proxy they hosted and they could count clicks this way. AOL controls the client so they could measure number of clicks on a link. I’ve heard trustworthy folks claim that ISPs are measuring clicks and that they’re not measuring clicks (any of the Barry’s want to comment?).
Without controlling the inbox, though, senders have to rely on proxy measurements to judge the effectiveness of any particular campaign. But at least email marketers have proxies to use for measurement.

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Don't take my subscribers away!

Tom Sather has a good summary of the problems with inactive email addresses and why data hygiene is critical to maintain high deliverability. These recommendations are some of the most difficult to convince people to implement.
Some of my clients even show me numbers that show that a recipient that hadn’t opened or read and email in 18 months, suddenly made a multi-hundred dollar purchase. Another client had clear numbers that showed even recipients that didn’t open for an entire year were responsible for 10% of revenue.
They tell me I can’t expect them to let their customers go. These are significant amounts of money and they won’t let any potential revenue go without a fight.
I understand this, I really do. The bottom line numbers do make it tough to argue that inactive subscribers should be removed. Particularly when the best we can offer is vague statements about how delivery may be affected by sending mail to unengaged users.
I don’t think many senders realize that when they talk about unengaged users they are actually talking about two distinct groups of recipients.
The first group is that group of users that actively receive email, but who aren’t opening or reading emails from particular senders. This could be because of their personal filters, or because the mail is going to the bulk folder or even simply because they don’t load images by default. This is the pool that most senders think of when they’re arguing against removing unengaged users.
The second group is that group of users that never logs in ever. They have abandoned the email address and never check it. I wrote a series of posts on Zombie Emails (Part 1, 2, 3) last September, finishing with suggestions on how to fight zombie email addresses.
Unlike senders ISPs can trivially separate the abandoned accounts from the recipients who just don’t load images. Sending to a significant percentage of zombie accounts makes you look like a spammer. Not just because spammers send mail to really old address lists, but a number of spammers pad their lists with zombie accounts in order to hide their complaint rates. The ISPs caught onto this trick pretty quickly and also discovered this was a good metric to use as part of their filtering.
I know it’s difficult to face the end of any relationship. But an email subscription isn’t forever and if you try to make it forever then you may face delivery problems with your new subscribers.

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