With email link authentication, SignatureAPI sends recipients an email containing a direct link to their signing ceremony. When recipients click the link, they’re automatically authenticated and can proceed with signing documents. This is the default authentication method when creating envelopes. If you don’t specify a ceremony configuration, SignatureAPI automatically uses email link authentication.

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When to Use

Email link authentication is ideal for straightforward signing workflows where:
  • You want the simplest possible experience for recipients
  • Recipients are comfortable checking their email to access documents
  • You don’t need to control the ceremony URL or send it through other channels
  • Security requirements allow email-based authentication
This method provides a familiar, one-click experience that most users expect when signing documents electronically.

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Ceremony Creation

You can create an email link ceremony automatically when you create a ceremony, or manually at a later time.

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On Envelope Creation (Automatic)

As a default, when you create an envelope, SignatureAPI automatically creates a ceremony with email_link authentication and sends an email to the recipient with a link to the ceremony.
Default Email Link Ceremony
// POST https://api.signatureapi.com/v1/envelopes
// X-API-Key: key_test_...
// Content-Type: application/json

{
    "title": "Service Agreement",
    "recipients": [
        {
            "type": "signer",
            "key": "client",
            "name": "John Doe",
            "email": "john.doe@example.com"
            // ceremony defaults to "email_link"
        }
    ],
    "documents": [ /* ... */ ],
    // ...
}
You can also set the recipient.ceremony explicitly, for example, to add another property to the ceremony, for example a redirect URL, to redirect the recipient after the ceremony is finalized.
Email Link Ceremony with Redirect URL
// POST https://api.signatureapi.com/v1/envelopes
// X-API-Key: key_test_...
// Content-Type: application/json

{
    "title": "Service Agreement",
    "recipients": [
        {
            "type": "signer",
            "key": "client",
            "name": "John Doe",
            "email": "john.doe@example.com",
            "ceremony": {
                "authentication": [
                    {
                        "type": "email_link"
                    }
                ],
                "redirect_url": "https://www.example.com/redirect"
            }
        }
    ],
    "documents": [ /* ... */ ],
    // ...
}

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Create Ceremony Endpoint (Manual)

To manually create an email link ceremony, use the Create Ceremony endpoint.
When you create a new ceremony for a recipient, any previous ceremonies are automatically revoked. This ensures that only the most recent ceremony remains active and accessible.
Create Email Link Ceremony
// POST https://api.signatureapi.com/v1/recipients/rec_123/ceremonies
// X-API-Key: key_test_...
// Content-Type: application/json

{
    "authentication": [
        {
            "type": "email_link"
        }
    ],
    // optional properties: redirect_to, etc ...
}

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Email Customization

SignatureAPI emails have a standard template. You can customize the following:
  • Email subject (taken from envelope.title)
  • Email message body (taken from envelope.message)
  • Email language (taken from envelope.language)
For example, an envelope with: 
{
  "title": "Dummy Agreement",
  "message": "Please take a moment to review the attached agreement at your convenience. Once you've completed your electronic signature, a copy of the signed documents will be automatically sent to your email for your records.\n\nIf you have any questions, feel free to reach out."
  //...
}
will produce an email similar to this:
If you need further email customization or want to use your own domain and email provider, you can use custom authentication to get the ceremony URL and build and send the customized email from your infrastructure.

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Audit Log

When recipients click the email link, they are automatically authenticated, and SignatureAPI records the timestamp for auditing purposes. The audit log indicates when email link authentication is used:
12/31/2025 11:59:59 PM
John Doe (#7161cf07) has authenticated using a secure link sent to john⁠@example.com.