Single email opt-in and double email opt-in solutions both have advantages and disadvantages. The advantages of using a single opt-in system include:

Easiest on the User: Single email opt-in is easiest on the subscriber. He or she won’t need to look for an extra email in his or her inbox or remember to click a confirmation link. The subscriber gets the instant satisfaction of beginning to receive email immediately.

Fastest Way to Build a List: As we’ll discuss below, one of the disadvantages of a double-opt in is that, often, people simply never confirm their subscription and you ultimately benefit from fewer sign-ups. This is particularly important if you’re paying to acquire email addresses. A single email opt-in will allow your list to grow more quickly. That speed may come at a cost, however.

Less Lost Email Addresses: With a double email opt-in, some subscribers will simply never remember to confirm their sign-up (or the confirmation email goes to spam). In that case, even though you did the hard work of convincing somebody to sign-up for your email list, you won’t be able to contact them and you will have essentially “lost” the email address.

Less Tech Resources Used: If you are using a third-party email marketing platform such as Comm100, you won’t need to allocate any additional tech resources to building out a double opt-in system if you want one. However, if you are building your own proprietary email marketing platform, a double opt-in will require more tech resources to build and a single-opt in may be a more effective solution to get your email marketing program up and running.

The disadvantages of a single opt-in email sign-up system include:

Less Respectful of Users’ Privacy: These days, individuals have a great concern about their online privacy. A single opt-in sign-up procedure is less concerned with privacy and information control, and some users will notice that and be concerned. Some online privacy certifications require that you use a double opt-in system.

Greater Risk to Your Sender Reputation: When you don’t use a double opt-in system, a number of bad addresses can enter into your email list. This includes mistyped email addresses, which can impact your sender reputation by adding to the statistics of undeliverable addresses that you’re attempting to mail to. You also risk having somebody who is not the owner of an email address enter the address into your newsletter box as a joke. Then, when the actual owner of that email address receives your email, he or she may mark you as spam and negatively impact your sender reputation.