CS&M
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.
What does open rate tell you
There has been an lot written about open rates in the past, but there are two posts that stand out to me. One was the EEC’s post on renaming open rate to render rate and Mark Brownlow’s excellent post on what open rate does and does not measure. I’ve also weighed in on the subject. The issue is still very confused.
If asked, most people will tell you that open rate is the number of emails that were opened by the recipient. The problem is that this isn’t actually true. Open rate is measured by the number of people that display an image in an email. Traditionally this has been a uniquely tagged 1×1 pixel, until some filters and mail clients stopped displaying 1×1 pixels. More recently, every image in an email is tagged, so opening one image would record as an open.
So open rate doesn’t actually tell a sender how many people opened and read an email. It really only records that an image in a particular email is loaded. It does not record when an email is opened. Some people don’t load images by default. Some people don’t load images at all, even when they open and actively read the text portion of the email.
Clearly, there are some uses for open rates. It can give a useful metric when comparing different forms of the same email (A/B testing) and when looking at user engagement over time. However, we have also recently seen that open rate is not predictive for click through rate.
When an open is not a sign of interest
A lot of people, including myself, are using opens as one of the measures of engagement. This, as a general rule, is not a bad measure. However, there are people who will open email not because they’re interested in it, but because they know it is spam.
Take, for instance, the email address I acquired in 1993. Yes, I still have this address. I stopped using it to sign up for lists in 1999 and stopped using it for most of the rest of my mail around 2001. This address, though, is on any number of spam mailing lists. The spam that gets through is usually sent by hard-core spammers. The ISP that hosts that mailbox uses Communigate Pro to filter mail, so much of the casual spam is filtered.
Generally, if I open an email (and load images or click through) on that account it is only in order to track down a spammer. For instance, I’m getting a lot of spam there from affiliates offering me the opportunity to purchase printing services for a very low price. I have actually been opening the mail, and clicking through. But I’m not clicking through because I’m interested in purchasing. I’m clicking through to see if my reports to abuse@ printer are resulting in any action against the spammers. (They’re not).
The thing is, though, I know that by clicking through on ads, I’ve now been promoted by the spammer to the “clicks on emails! it’s a live address!” list. Which only means I’m going to get more spam from them. Lucky me.
Using clicks and opens as a measure of engagement isn’t necessarily bad. But when using them you have to understand the limitations of the measurement and that what you may think it’s telling you isn’t actually what it’s telling you.
Failed delivery of permission based email
A few weeks ago, ReturnPath published a study showing that 20% of permission based email was blocked. I previously discussed the definition of permission based email and that not all the mail described as permission based is actually sent with the permission of the recipient. However, I only consider this a small fraction of the mail RP is measuring, somewhere in the 3 – 5% range. What happens with the other 17 – 15% of that mail? Why is it being blocked?
There are 3 primary things I see that cause asked for and wanted email to be blocked.
Permission Based Emails? Are you sure?
Yesterday I wrote about the ReturnPath study showing 21% of permission based email does not make it to the inbox. There are a number of reasons I can think of for this result, but I think one of the major ones is that not all the mail they are monitoring is permission based. I have no doubt that all of the RP customers say that the mail they’re sending is permission based, I also have no doubt that not all of the mail is.
Everyone who sends mail sends permission based email. Really! Just ask them!
In 10 years of professionally working with senders I have yet to find a marketer that says anything other than all their email is permission based. Every email marketer, from those who buy email addresses to those who do fully confirmed verified opt-in with a cherry on top will claim all their email is permission based. And some of the mailers I’ve worked with in the past have been listed on ROKSO. None of these mailers will ever admit that they are not sending permission based email.
Going back to ReturnPath’s data we don’t really know what permission based email means in this context and so we don’t know if the mail is legitimately or illegitimately blocked. My guess is that some significant percentage of the 20% of email to the probe accounts that doesn’t make it to the inbox is missing because the sender does not have clear recipient permission.
When even spammers describe their email as permission based email marketing, what value does the term have?
Delivery Metrics
Last week ReturnPath published a study that shows 20% of permission based email fails to be delivered to the inbox. For this study, ReturnPath looked at the mail sent by their mailbox monitor customers and counted the number of deliveries to the inbox, the number of deliveries to the bulk folder and the number of emails that were not delivered.
At US ISPs 21% of the permission based emails sent to the ReturnPath probe network did not make it to the inbox. 3% of the emails sent went to the bulk folder and 17% did not make it to the mailbox at all. MSN/Hotmail and Gmail were the worst ISPs to get mail to. They each failed to deliver more than 20% of the mail that was sent to them. At Canadian ISPs, even less of the mail made it to the inbox, primarily because primus.ca is such a large portion of the Canadian market and they use Postini as a filter. Postini is a quite aggressive filter and takes no feedback from senders.
ReturnPath’s take home message on the survey is that one set of metrics is not enough to effectively evaluate a marketing program. Senders need to know more about their mailings than they can discover from just the bounce rate or the revenue rate or response rate or open rate.
There are a lot of reasons an email doesn’t get to the recipient’s inbox or bulk folder. Mail can be hard blocked at the MTA, and rejected by the ISP outright. Mail can be soft blocked at the MTA and the ISP can slow down sending. Sometimes this is enough to cause the sending MTA to stop attempting to deliver the mail, thus causing mail to not show up. Both of these types of blocks are usually visible when looking at the bounce rate.
Some ISPs accept mail but then fail to deliver it to the recipient. Everything on the sender end says the ISP accepted it for delivery but the ISP just drops it on the floor. This is the type of block that a mailbox monitoring program is best able to identify.
Despite all the discussions of numbers, many marketers are still not measuring the variables in their email campaigns. Ken Magill wrote today about a study released by eROI that indicates more than a third of marketers are not doing any testing on their mailings.
Now, both of these studies are done in an attempt to sell products, however, the numbers discussed should be making smart senders think about what they are measuring in regards to their email campaign, how they are measuring those factors and what the measurements mean.
Reputation as measured by the ISPs
Part 3 in an ongoing series on campaign stats and measurements. In this installment, I will look a little closer at what other people are measuring about your email and how that affects your reputation at the ISPs.
Part 1: Campaign Stats and Measurements
Part 2: Measuring Open Rate
Reputation at the ISPs is an overall measure of how responsive recipients are to your email. ISPs also look at how much valid email you are sending. Anything the ISP can measure and use to distinguish good mail from bad is used in calculating reputation.
Some of the major metrics ISPs use include the following.
Invalid Address Rates
The ISPs count how much mail from any particular IP address is hitting non-existent addresses. If you are mailing a large number of email addresses that do not exist (550 user unknown), this is a suggestion that your address collection techniques are not very good. Responsible mailers do have the occasional bad address, including typos, expired/abandoned addresses, but the percentage in comparison to the number of real email addresses is low. How low is low? Public numbers suggest problems start at 10% user unknowns, but conversations with ISP employees show they consider lower levels a hint there may be a problem.
To calculate bounce rate ISPs take the total number of addresses that were for invalid accounts and divide that by the total number of addresses that the sender attempted to send mail to. Rates above 10% may cause significant delivery issues on their own, rates lower that 10% may still contribute to poor delivery through poor reputation scores.
Spamtraps
ISPs pay a lot of attention to how much mail is hitting their “trap” or “bait” accounts. There are a number of different sources of these trap accounts: old abandoned email addresses, addresses that never existed or even role accounts. Hits to a trap account tells the ISP there are addresses on your list that did not opt-in to receive mail. And if there are some addresses they know about that did not opt-in, it is likely that there are other addresses that did not opt in.
Spamtraps tend to be treated as an absolute number, not as a percentage of emails. Even a single spamtrap on a list can significantly harm delivery. According to the ReturnPath Benchmark report lists with a single spamtrap had nearly 20% worse delivery than lists without spamtraps.
This is spam clicks (FBL complaints)
Complaints from users are heavily used by ISPs. This tells them directly how many people are objecting to your email. In this case, permission is removed from the equation. Even if a sender has permission to send email, the recipient can say “no, I don’t want this, it is spam.” The ISPs put more weight on what their users tell them than on what the senders tell them.
Measuring open rate
In this part of my series on Campaign Stats and Measurements I will be examining open rates, how they are used, where they fail and how the can be effectively used.
There has been an lot written about open rates recently, but there are two posts that stand out to me. One was the EEC’s post on renaming open rate to render rate and Mark Brownlow’s excellent post on what open rate does and does not measure. I’ve also weighed in on the subject.
Overall, I find open rates to be a very frustrating metric. Some senders, particularly those relatively new to email marketing, are so sure they know what open rate is and what it means, that they don’t take any time to actually understand the number. While the name “open rate” seems self explanatory, it’s actually not. Open rate is actually not a measure of how many recipients open an email. However, there are times where open rate is a useful metric for measuring a marketing program over time.
What is an open?
If asked, most people will tell you that open rate is the number of emails that were opened by the recipients. The problem is that this isn’t actually true. An open is counted when a tagged image in an email is rendered by the recipient’s email client. Not all mail clients render images by default, but the emails are still available for the recipient to read. If a user clicks on a link in an email that has not had an image rendered, some ESPs count that as an open as well as a click. In other cases, visiting a link in an email with no image rendered is just a click, no open is recorded.
What is the open rate?
Open rate is generally the percentage of email opens divided by some number representing the number of emails sent. Many senders use the number of emails sent minus the number of bounced emails, others use just the number of emails sent without factoring in the number of emails bounced.
Open rate is a secondary metric. While it does not measure the success, or failure, of a campaign directly, it can be used as a indicator for campaigns. Many people use open rate as a metric because it’s easy to measure. Direct metrics, such as clicks or average purchase or total purchase, may take days or even weeks to collect and analyze. Open rates can be calculated quickly and easily.
What the open rate isn’t
Open rate is not a measure of how many people opened a mail. It is not a measure of how many people read a mail. It really only records that an image in a particular email is loaded and, sometimes, that a link was clicked on. Open rates can be wildly different depending on how the sender measures opens and how the sender measures sends.
What senders use open rates for
To compare their open rates with industry averages
As I talked about above, this use of open rates is problematic at best. You cannot compare numbers, even when they have the same name, if the numbers were arrived at using different calculations. Open rate is not open rate and unless you know the underlying algorithm used you cannot compare two open rates. This is a poor use of open rate.
As a metric for advertising rates
Since a sender can manipulate the open rate by using different calculation methods, this is a good metric for the advertiser to use. It is not so great for the purchaser though, who is at the mercy of the sender’s metrics. There are contractual ways a purchaser can protect herself from an unscrupulous marketer, but only if she understands how open rate can be manipulated and takes steps to define what open rate is in use.
To judge the success of campaigns over time
A single open data point doesn’t mean very much, however, using consistently measured open rates a sender can measure trends. Open trends over time are one area that open rates can help senders judge the success, or failure, of a marketing campaign.
As one metric in A/B testing
Comparing open rates in A/B testing gives some indication of which campaigns recipients may be more interested in. As with trends over time, the lone measurement isn’t useful, but as a comparative metric, it may provide senders with insight into a particular mailing.
To judge the engagement of recipients
Over the long term, recipients who do not interact with a mailing become dead weight on the list. Too many non responders can hurt a sender’s reputation at an ISP. List hygiene, in the form of removing people who never open or click on an email, is an important part of reputation management.
As metrics for email campaigns go, open rate is limited in what it measures about an email campaign. However, as a quick way to measure trending or do head to head comparisons it is a useful metric.
Campaign stats and measurements
Do you know what your campaign stats mean? Do you know what it is that you’re measuring? I think there are a lot of emailers out there who have no idea what they are measuring and what those measurements mean.
The most common measurement used is “open rate.” There’s been quite a bit of discussion recently about open rates, how they’re calculated, and is there a better way. In my own opinion, open rate can be useful, but only in some circumstances. More often it is a distraction from real measurements
Not only has there been the recent discussions about “open rate” versus “render rate” and a lot of confusion among people about what the underlying issues are, but I’ve also been working through some campaign stats questions with other people that indicate maybe they don’t actually understand the numbers they’re using.
For instance, what do the delivery statistics reported by the various mailbox monitoring companies mean? If you have 100% inbox delivery as measured by the program, does that mean all your mail has reached the recipient’s inbox?
What about bounce rates? Everyone says “keep them low” but what does low mean? How do you measure them?
Over the next few posts, I’ll talk about the different stats and measurements in common use and what they do and don’t mean.