The mailing must be of the type confirmation.
**Type**: long
**Parameters**
| Name | Type | Value |
| sessionId | String | ID of the session |
| Name | String | Internal name of the opt-in process |
| Description | String | Internal description of the opt-in process |
| mailingId | long | ID of the mailing that is used for the opt-in process |
| confirmationUrl | String | URL of confirmation page to which the recipient is directed to complete the registration process |
**Return values**
ID of the opt-in process
**Code structure**