When someone signs up to your email list, there are two ways to add them.
- Single opt in: they type their email, click subscribe and are immediately on your list.
- Double opt in: they type their email, click subscribe, then get a confirmation email. They only join your list after clicking the confirmation link.
It sounds like a small detail. It has a real effect on the health of your list and how many of your emails reach the inbox.
The case for single opt in
- Faster growth. Some people never click the confirmation email, so single opt in usually adds more subscribers.
- Less friction. Signing up is one step instead of two.
- Good for in person signups where you collect emails directly, such as at a shop counter, as long as people clearly agree.
The case for double opt in
- No typos. If someone types gmial.com, they never confirm and never join. That means fewer bounces.
- No fake signups. Bots and pranksters cannot fill your list with addresses that do not belong to them.
- Fewer spam traps. Planted addresses cannot confirm, so they never reach your list.
- Proof of consent. You have a clear record that each person confirmed they wanted your emails. This is helpful in places with strict privacy laws.
- More engaged subscribers. People who confirm are showing real interest, which often means better opens, clicks and replies.
All of these protect your sending reputation, which helps every future email reach the inbox.
What about lost subscribers?
Yes, some people will not confirm. But many of those were never going to read your emails anyway, or they mistyped their address. A slightly smaller list of real, interested people usually earns more than a bigger list padded with dead weight, and it often costs less too, because many tools charge by list size.
How to get more people to confirm
If you use double opt in, make confirming easy:
- Tell people what happens next on your thank you page: "Check your inbox and click the link to confirm. It may take a minute."
- Write a clear confirmation email with a short subject, such as "Please confirm your subscription", and one big button.
- Use your normal sender name so people recognise it.
- Remind them to check spam or Promotions on the thank you page.
- Deliver the reward after confirming. If you offer a free guide, send it in the confirmation step. People will click to get it.
Which should you choose?
For most people, double opt in is the safer choice, especially if:
- Your signup form is public on your website.
- You offer a free download, which attracts more fake and throwaway signups.
- You have had problems with spam, bounces or bots before.
- You have subscribers in places with strict privacy rules.
Single opt in can work if you collect emails in controlled ways and watch your bounce and complaint rates closely.
A middle ground
Some senders use single opt in but send a welcome email immediately and remove anyone who bounces or never engages in their first few weeks. This keeps signups high while still protecting the list. It needs more attention than double opt in, so it suits people comfortable watching their numbers.
The short version
Single opt in grows faster. Double opt in grows cleaner. If inbox placement matters to you, and it should, double opt in is the steadier long term choice.
Mailbox providers update their filters and requirements regularly. This guide was last reviewed on March 25, 2025. Spotted something out of date? Tell us.