Adding Contacts and Creating Your Trigger
Add any contacts that require opt-in confirmation to Bronto with a status of Unconfirmed. Unlike the Onboarding status, Unconfirmed contacts are Inactive and cannot receive marketing emails until they move to the Active status. For a recap on contact statuses, check out Back to Basics: Conquering Contact Status. If you use the SOAP API to add contacts to Bronto, you can specify the Unconfirmed status in your addContacts call. If you’re using Direct Add to add contacts to Bronto, you can add the &doubleOptin=1 parameter to set the status to Unconfirmed. You should also create a list you can use to trigger the subscription confirmation message. Be sure you’re adding contacts to this list when you add them to Bronto as Unconfirmed as this will be the trigger for your workflow. 
As shown above, the workflow is triggered when a contact is added to the double opt-in trigger list. You can then use a contact field comparison node to ensure only the Unconfirmed contacts go on to receive the subscription confirmation message – just in case any contacts in another status end up on the list. It’s important to remove contacts from the trigger list immediately afterward so they can trigger the workflow again should they attempt to sign up again. Remember: A contact cannot be added to a list if they’re already on it! Note: You can also run double opt-in on contacts you manually import from a csv file. On the Confirm Contact Subscription step of the import, select Send them a subscription confirmation message, which will allow you to bypass the workflow method. Choosing this option will set the imported contacts to Unconfirmed and send your selected confirmation email. If you’re using an Add Contacts webform to capture contacts, you can use the Form Settings to add contacts with a status of Unconfirmed and select a subscription confirmation message to send. 
Creating Your Confirmation Message
The subscription confirmation message will be sent as a transactional delivery, so don’t fill this up with marketing content. A clear and simple call to action to confirm the subscription is best. The CTA link should use the %%!confirm_url%% tag, as this will redirect contacts to the Default Subscription Confirmation webform. You might also include a summary of what the contact is consenting to, such as the marketing terms surrounding their receiving your personalized marketing content.
When Unconfirmed contacts land on a subscription confirmation type webform, their status changes to Active, hence, their subscription is confirmed. You can style this page and customize the copy however you like, but you should consider including a link to manage preferences or unsubscribe in case anyone has changed their mind or reached this page by mistake. 
Adding Confirmed Contacts to Other Lists
At this point, your contacts have confirmed their subscription, we’ve captured their consent and their status is Active. But one more simple workflow will allow you to ensure these contacts are added to any specific list(s). 
Use the Webform Event node to trigger a workflow when a contact views your subscription confirmation webform. Follow this up with a Change List Membership node (or nodes) to add the contacts to your desired list(s). Remember that any contacts that never confirm their subscription will remain Unconfirmed indefinitely. You could even take this workflow a step further and send a series of welcome emails once contacts have confirmed their subscription. Bronto does not require that contacts are run through double opt-in, but it can help you ensure that only legitimate, high-quality subscribers make it onto your list and capture a clear trail of their consent. If you have any questions about implementing double opt-in or how it can benefit you, contact your account manager about enlisting the help of our Professional Services team.