Ever since I started my newsletter — which is now in its 20th year — I have used a double opt-in system. What does that mean, and why do I do it?

What is meant by single opt-in and double opt-in?

A single opt-in is where you fill in the sign-up form and then click Send or OK (possibly after proving that you’re not a robot). That’s it. You are now subscribed.

A double opt-in system is where you go through the steps above, and then receive an email asking you to confirm that you really do wish to subscribe. If you don’t answer, then you won’t receive the newsletter. This is the system I prefer, and always have, so the question is: why?

The advantages of double opt-in

The first reason is that there may be people out there who have the same mentality as my friends and I had when we were 9 years old. Every so often, for a laugh, one of us would sign up another one of us to receive Army recruitment information. I can imagine there are people around now who sign up others to receive newsletters either for a joke or to have them bombarded with unwanted emails. A single opt-in system makes that easy to do. I suppose if you were technically proficient enough you could circumvent a double opt-in approach, but most people aren’t and don’t.

Next, the internet is full of spambots that fill in lots of forms with fake email addresses. For why they do that, see How to Protect My Website from Spam Bots and Fake Signups. There are several possible consequences of this.

One is that if a spambot can sign up to your newsletter, it can potentially do other things too, because it has benefitted from a weakness in your system. I’m not sure how far the box to tick that you’re not a robot helps, because I’ve found that some spambots manage to get through the initial sign-up stage anyway. Perhaps there would be more fake sign-ups without that in place.

Another issue is that you want quality subscribers. It may be useful to be able to tell advertisers and others that you have a mailing list of 20,000, but if 19,000 of them are fake that’s not very honest.

That will also play havoc with your open rate. This is the percentage of people who open your newsletters. If your open rate is, say, 20% of your genuine subscribers, of which in my example there are 1,000, that will make your overall open rate 1% (200 out of 20,000). That means that 99% of your subscribers don’t open your newsletter. Not a great look.

You will also have a high rejection rate. I always email unconfirmed sign-ups every so often to remind them to confirm their subscription. When I do, I always get a batch of “Email undeliverable” messages, as shown in the screenshot below.

All of the emails shown were rejected because the email addresses don’t exist. Thank goodness they didn’t get as far as being on my mailing list.

A high rejection rate will almost certainly result in Google regarding your emails as spam. It may even result in your mailing list company to block you from using their service, because sending out spam will affect their reputation. And that’s another thing: why risk acquiring a reputation as a spammer?

Also, although data protection legislation in the UK has never made double opt-in mandatory (unless they changed that when I wasn’t looking), it seems to me to be good practice anyway in that regard. It means that you are saying to the would-be subscriber, in effect: “Look, are you absolutely sure you wish to provide me with your name and email address?”

It suggests that you take the business of looking after people’s data and earning their trust seriously.

Double opt-in does have a disadvantage for both the newsletter supplier and the potential subscriber. For the former, there is the possibility that people don’t see the “Please confirm” email, perhaps because it has gone in their spam folder. That means they have fewer subscribers than they otherwise might have. For the latter, it’s one extra step, one extra bit of hassle.

I think those disadvantages are a price worth paying.