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Overview

Double opt-in requires new contacts to confirm their email address before they become subscribed. When enabled on a contact book, newly added contacts receive a confirmation email with a verification link. Only after clicking the link do they become fully subscribed. Why use double opt-in?
  • Ensures email addresses are valid and owned by the subscriber
  • Reduces bounce rates and spam complaints
  • Improves deliverability and sender reputation
  • Helps comply with email marketing regulations (GDPR, CAN-SPAM)

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How it works

1

Contact is added

When a contact is added to a contact book with double opt-in enabled (via dashboard, API, or CSV import), they are created with a Pending status instead of being immediately subscribed.
2

Confirmation email is sent

A confirmation email is automatically sent to the contact with a unique verification link. The link is signed with HMAC-SHA256 and expires after 7 days.
3

Contact confirms

The contact clicks the verification link in the email and confirms their subscription on the confirmation page.
4

Contact is subscribed

The contact’s status changes from Pending to Subscribed and they will now receive your emails.

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Enabling double opt-in

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Via the dashboard

  1. Go to Contacts and select a contact book
  2. Click on the Double Opt-In tab
  3. Toggle double opt-in on
  4. Customize the confirmation email (optional)
  5. Save your changes

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Via the API

Create a contact book with double opt-in enabled: 
curl -X POST https://app.usesend.com/api/v1/contactBooks \
  -H "Authorization: Bearer us_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Newsletter Subscribers",
    "doubleOptInEnabled": true,
    "doubleOptInFrom": "Newsletter <[email protected]>",
    "doubleOptInSubject": "Please confirm your subscription"
  }'
Or enable it on an existing contact book: 
curl -X PATCH https://app.usesend.com/api/v1/contactBooks/{contactBookId} \
  -H "Authorization: Bearer us_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "doubleOptInEnabled": true
  }'

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Contact statuses

When double opt-in is enabled, contacts have three possible statuses:
StatusDescription
SubscribedContact has confirmed their subscription and will receive emails
PendingContact has been added but hasn’t confirmed yet
UnsubscribedContact has explicitly unsubscribed
Contacts with Pending status will not receive campaign emails. They will only receive the double opt-in confirmation email.

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Customizing the confirmation email

You can customize three aspects of the confirmation email:

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From address

Set a custom sender address for confirmation emails. The address must use one of your verified domains. 
{
  "doubleOptInFrom": "Newsletter <[email protected]>"
}
If not set, the confirmation email will be sent from the first available verified domain.

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Subject line

Customize the email subject. The default is “Please confirm your subscription”. 
{
  "doubleOptInSubject": "Confirm your subscription to our newsletter"
}

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Email template

The confirmation email body can be customized using the useSend email editor (via the dashboard) or by providing the editor JSON content via the API.

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Template variables

The following variables can be used in the confirmation email template:
VariableDescription
{{doubleOptInUrl}}The confirmation link (required)
{{email}}The contact’s email address
{{firstName}}The contact’s first name
{{lastName}}The contact’s last name
The {{doubleOptInUrl}} variable is required in the email template. The confirmation email cannot be saved without it. This ensures every confirmation email contains a working verification link.

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Resending confirmation emails

If a contact hasn’t confirmed their subscription, you can resend the confirmation email from the dashboard:
  1. Go to your contact book and find the pending contact
  2. Click the Resend button next to the contact
Each resend generates a new confirmation link with a fresh 7-day expiration window.

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Best practices

Double opt-in requires at least one verified domain to send confirmation emails. Make sure to verify your domain before enabling double opt-in.
The confirmation email should be clear and concise. Include a prominent confirmation button and a brief explanation of what the subscriber is confirming.
Use a from address that your subscribers will recognize, such as [email protected] or [email protected]. This reduces the chance of the confirmation email being marked as spam.
Regularly check for contacts stuck in Pending status. If many contacts aren’t confirming, consider improving your confirmation email or resending confirmations.