The One-Time Password via Email (OTPvE) authentication method is a single-factor identity verification method that requires the recipient to enter a passcode that they must retrieve from the recipient's email box.

Because the one-time passcode is delivered to the same email address as the original signature link, the OTPvE authentication method is considered a single-factor authentication method. However, OTPvE does not require the user to create an account or otherwise log in to another application (as Acrobat Sign authentication does). Access to the email box is all that is required, making this method lower friction in many cases, particularly for external users.

Using OTPvE provides additional security beyond simply relying on the email link. For example:

Access to an email does not mean that the email box is compromised. In the event that an email link is exposed but the email box is secured, the OTMvE authentication will maintain the security of the agreement.
If an agreement email is improperly forwarded (vs. proper delegation), the OTPvE challenge will prevent the agreement from being accessed, preserving the audit report integrity regarding the identified signer's email and the actual signer.

Successful authentication requires the recipient to enter the passcode within 60 seconds of requesting the code.

Availability:

One-Time Password via Email is available for enterprise license plans only.

Configuration scope:

The feature can be enabled at the account and group levels.

Note:

One-Time Password via Email is not a metered service. There is no charge for use, regardless of volume.

How it's used

After selecting the Review and sign link, the recipient is delivered to the one-time verification code page.

The recipient must select the Send Code button to have the code delivered to their email address.

Once the code is obtained, copy and paste it into the Verification Code text box and select Verify.

Once the authentication is passed, the recipient can interact with the agreement.

If the recipient closes the agreement window for any reason before completing their action, they must re-authenticate to resume.

Configuring the One Time Password method when composing a new agreement

When OTPvE is enabled, the sender can select Email OTP from the Authentication drop-down just to the right of the recipient's email address:

Best Practices and Considerations

OTPvE isn't a second-factor authentication and should not be used when the signature requires additional authentication (beyond email authentication).
OTPvE requires that the recipient have direct access to the email box to which the agreement was delivered.
The OTPvE method is best used for external authentication that requires some form of logged authentication method but does not demand a second-factor authentication.
When recipients access agreements directly from the Acrobat Sign Manage page, OTPvE is the primary (and only) authentication factor. The email link (typically providing the default primary authentication element) is bypassed and replaced with the authenticated session to Acrobat Sign.

Configuration Options

OTPvE authentication has two sets of controls, which are available to be configured at the account and group levels:

Send Settings, which control the sender's access to the password option
Security Settings, which govern the recipient's experience

Send Settings

Group and account-level admins can enable and configure the OTPvE Send Settings by navigating to Send Settings > Signer Identification Options.

There are five valuable controls relevant to the OTPvE method:

Email One Time Password - The core feature; checking this box enables access to the authentication method for senders when composing agreements.
By default, use the following method - Defines the default value inserted into the recipient's Authentication option on the Send page.
Identity authentication for internal recipients - Enabling this option allows internal recipients to be configured with different authentication options and defaults.
Don't challenge the signer to re-authenticate if they are already logged in to Acrobat Sign - When enabled, the recipient isn't challenged to re-authenticate when opening an agreement if they are already authenticated to the Acrobat Sign service.
- This requires the agreement to be opened in the same browser as the authenticated session to Acrobat Sign.

Support contact - By default, the challenge page for the recipient requiring them to request the one-time passcode provides the email address of the sender if the recipient needs to contact someone. The optional Support contact field replaces the sender's email address with either a phone number or an email address, providing a funnel for inbound queries to a resource dedicated to resolving issues.

Support contact information in the OTPvEm recipient challenge

Security Settings configuration

The Security Settings page has one control for the OTPvE method to limit the number of failed attempts that a recipient can try before the agreement is automatically canceled.

Audit Report

The audit report clearly indicates when the recipient successfully applies the Email OTP authentication method.

Automatic agreement cancelation when a recipient fails to authenticate

If the settings restrict the number of authentication attempts, and the recipient fails to authenticate that number of times, the agreement is automatically canceled.

The agreement's originator is sent an email announcing the cancelation with a note identifying the recipient who failed to authenticate.

No other parties are notified.

The audit report reflects the cancelation and the reason:

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One Time Password via Email

Overview