This is a short sample from my guide to html email design and best practices called Modern HTML Email. You can learn more about the guide here.
Apart from the content of your email campaign, permissions are the single most important part of email marketing. If you screw up the permissions, you’re going to have a bad time.
There are very few cases in which you do not actually need a user’s permission to send them an email. Even in those cases, it is a good practice to get the user’s permission anyway. For our purposes, let’s just go ahead and assume that you need to get a subscriber’s permission before sending any emails.
There are two methods to obtaining a user’s permission. These methods are known as the single opt-in method and the double opt-in or confirmed opt-in method. Both start out the same way, with someone deliberately adding their email address to a list via a form on your website, a form on one of your social networks, or in person. For the single opt-in method, no further action is required on the part of the user before you can start sending emails. However, the double opt-in method requires an intermediate step before you can start sending emails. This step usually takes the form of you sending an email with a confirmation link that the user must click to confirm their subscription.
Before deciding on a method of collecting subscribers, it is important to understand the benefits and drawbacks of both methods. Let’s start with the single opt-in method.
It is generally easier to grow your subscriber list using the single opt-in method than the double opt-in method. Because there are no extra steps in the single opt-in process, it is easy for subscribers to quickly sign up and start receiving emails. Though single opt-in subscriber lists tend to grow more quickly and end up larger than double opt-in subscriber lists, the single opt-in method is not without flaws. A major drawback of using the single opt-in method is that there is a fair chance that a significant percentage of the subscribers will have entered bad email addresses, or may not even be real people to begin with. By failing to confirm the email addresses submitted by subscribers, you may find yourself sending to bots and bad email addresses, which will lead to high bounce rates and a poor sending reputation.
It is not as easy to grow your subscriber list using the double opt-in method. Because there is an extra step required of the subscribers, your subscriber list will probably grow at a slower rate and likely be smaller than if you used the single opt-in method as a result of subscribers failing to follow through with the confirmation step. However, this smaller list is not necessarily a drawback. At least in theory, the subscriber list generated using the double opt-in method should be cleaner and more responsive to your marketing efforts. The thinking is that because the subscribers actively confirmed their subscriptions, they are more likely to pay attention to and act on your campaigns than the passive subscribers on a single opt-in list.
Traditionally, the accepted best practice is the double opt-in method. However, both subscribers and email marketers have recently expressed a preference for the single opt-in method. This is likely because the single opt-in method eases the burden of confirmation on the subscriber’s end and ensures quicker list growth on the marketer’s end. Email Wizardry’s Nicole Merlin expresses this view:
When determining which of the two methods to employ in your email campaigns, the most important factor to consider is your targeted audience. If you are marketing to a narrow segment, chances are that you can safely use the single opt-in method without worrying too much about subscribers submitting bad email addresses. If people are interested in a niche market, then they will likely more readily (and accurately) give out their email addresses, which will lead to a nice, clean subscriber list. On the other hand, if you are working in a massive industry and collecting subscribers via a heavily trafficked website, the double opt-in method is probably the way to go. Requiring subscribers to actively confirm their subscription will help weed out the bots and bad email dresses that will likely be submitted in such an environment and result in a cleaner subscriber list. Basically, determining which method to use is a numbers game. The likelihood of a subscriber list being clean decreases as the list grows, so if you believe your means of collecting email addresses will result in a large yield, it is probably best to employ the double opt-in method.
There is another way to obtain a subscriber list, but I did not include it above as one of the methods for obtaining permissions because I would never recommend it. This means of obtaining subscribers is renting or buying an email subscriber list. There are several places that market and sell huge subscriber lists, but it is never worth purchasing one. The subscribers on these lists opted into something, but the thing they opted into was not your list. Chances are that such lists were illegally harvested and are extremely unreliable. If you start marketing to one of these lists, don’t be surprised by how many emails bounce and how quickly your sender reputation nosedives.
Finally, it is important to keep in mind that even if you have a good list and explicit permission from subscribers, you still need to keep that list warm. It is key to actively engage your list so the subscribers do not forget who you are. There is a fine balance you need to maintain: on the one hand, you don’t want to over-send and risk being labelled spam; on the other hand, you don’t want to send so infrequently that subscribers forget they gave you permission and mark you as spam. A good rule of thumb in ensuring that your list is warm is to send an email at least every few months. I’ve seen some people claim that a list has up to 18 months before it should be considered cold, but I strongly disagree. Do you remember signing up to a newsletter more than a month or two after it happened? I didn’t think so. If you haven’t sent an email to your list in a few months, it has grown cold.
If you realize that you have allowed a list to go cold, a good practice is to send out a campaign to renew your subscribers’ permissions. The software company Panic does an excellent job of this. It sends out reminders of how you got on its subscriber list along with an easy way to confirm your interest in continuing to receive emails.
Employing a practice such as Panic’s is key to both keeping subscribers happy and keeping subscriber lists clean, particularly when you only occasionally send to your subscriber list.
In addition to obtaining permission from your subscribers, you must also be aware of the law surrounding email marketing and the ways in which your emails may be marked as spam. These considerations are further explored in the guide.