How to set up double opt-in for your subscribers

Use double opt-in to make sure new subscribers truly want to hear from you—and to keep your list engaged, compliant, and spam-free.

This guide explains:

• What double opt-in is and how it works in Flodesk

• How to enable and customize it for your forms

• When the double opt-in email is and is not sent

• How to resend confirmation emails

• How to troubleshoot double opt-in deliverability issues
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Double opt-in is a two-step subscription process that asks subscribers to confirm their email address before they’re added to your list.

Here’s how it works:

1. A visitor submits your opt-in form (first permission).

2. Flodesk automatically sends them a confirmation email.

3. The subscriber clicks the confirmation button in that email (second permission).

4. Only after clicking the button are they added to your audience.

Until they confirm, the subscriber is marked as Unconfirmed in your Audience and appears greyed out.

Important:
Flodesk will not send campaigns or workflows to unconfirmed subscribers.

This is a common point of confusion, so here’s the rule clearly stated:

• Brand-new subscribers who are not yet in your Flodesk Audience

• Existing, already-active subscribers who opt in again through another one of your forms

• Subscribers who were previously confirmed

Even if double opt-in is enabled on the form, existing subscribers will not receive the confirmation email again.

Double opt-in helps you:

• Stay compliant with your country's email marketing and spam regulations

• Prevent bots and fake email addresses from joining your list

• Build a more engaged, higher-quality audience

• Protect your sender reputation and deliverability

Double opt-in is not enabled by default and must be turned on per form.

1. Go to your Forms dashboard

2. Hover over the form you want to update

3. Click the three dots ( … ) on the form card

4. Select Settings

5. Toggle Double opt-in ON

6. Click Customize opt-in message

This opens your Account settings → Opt-in setup in a new tab.

Your confirmation email’s only job is to get the subscriber to click the confirmation button.

Best practices:

• Keep the design short and minimal

• Focus on one clear call-to-action

• Avoid adding extra links or distractions

Flodesk’s default template is already optimized for high confirmation rates. Adding too much content can reduce conversions.

Important notes:

• The email always sends from your default sending address

• The subject line cannot be changed (this helps inbox placement)

• Replace the default Flodesk signature with your business signature

• Use the paper plane icon to send yourself a test email

Only subscribers who click the confirmation button will be added to your list.

After confirming, subscribers see your Thank You page.

You can:

• Edit the header and message text

• Thank them for joining

• Let them know what emails to expect

• Link back to your website

• Add social links or a custom URL

Clicking the logo on this page redirects subscribers to your website.

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​​​Once you've finished customizing your Thank you page click Finish at the top.
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• Your double opt-in email and Thank You page are account-wide, not form-specific

• You only need to customize them once

• You must enable double opt-in separately for each form

• Turning it on for one form does not enable it for all forms

• Existing active subscribers will never receive the confirmation email again

If a subscriber hasn’t confirmed:

1. Go to Audience

2. Filter or select the Unconfirmed subscriber(s)

3. Click Resend opt-in → Resend now

Resend rules:

• You can resend the email as many times as needed

• You must wait 24 hours between sends to the same subscriber

If subscribers say they didn’t receive the confirmation email, check the following:

1. Ask them to check spam and promotions folders

Confirmation emails are automated and can sometimes be filtered.

2. Verify the email address was entered correctly

Typos are a very common cause of missing confirmation emails.

3. Confirm they are a brand-new subscriber

Existing subscribers will not receive the double opt-in email again.

4. Send a test to yourself

Use the test send option to confirm inbox placement.

5. Check your sending domain setup

Using a custom domain email with proper authentication (SPF, DKIM, DMARC) improves deliverability.

6. Resend after 24 hours

If the subscriber is still unconfirmed, resend the opt-in email manually.

Double opt-in ensures subscribers genuinely want to hear from you by requiring email confirmation before they’re added to your list.

• Enable it per form

• Customize the confirmation email and Thank You page once

• Only brand-new subscribers receive the opt-in email

• Unconfirmed subscribers won’t receive campaigns

• You can resend the confirmation email after 24 hours

When used correctly, double opt-in improves compliance, engagement, and deliverability.

What is double opt-in?
Double opt-in is a two-step signup process where subscribers must confirm their email address before being added to your list.

Is double opt-in enabled by default?
No. You must enable it individually for each form.

Will existing active subscribers receive the double opt-in email?
No. Double opt-in emails are only sent to brand-new subscribers.

Can I manually confirm a subscriber?
No. Subscribers must confirm themselves by clicking the confirmation button.

Can I resend the double opt-in email?
Yes. You can resend it every 24 hours to unconfirmed subscribers.

Why isn’t someone receiving the confirmation email?
Common reasons include spam filtering, email typos, or the subscriber already being active in your audience.