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    7.2.4 • Public • Published

    Email Subscription Widget with Double Opt-In

    Note: This is not an officially supported Twilio SendGrid library

    This is an open source repository to add a flexible email subscription widget, like the one shown below, to any website using Twilio SendGrid. After following these directions, you'll be able to add a snippet of HTML to any website that will collect email addresses for your app or business. This widget utilizes double opt-in functionality, which means users must confirm their email addresses by clicking an email that is automatically sent to their provided email address.

    alt text


    Before following these instructions, you must:


    Initial Twilio SendGrid Set-up - Create API Key & Contact List

    To begin, you will first need to create an API key on Twilio SendGrid's website. Once logged in, go to Settings -> API Keys, and click the blue button in the top right corner of the website. You will be creating a General API key, which must have Full Access to Mail Send and Marketing Campaigns. Keep this API key in a safe and private location. You will need it later.

    Fork this Repository to Create Your Copy

    If you are unfamiliar with GitHub, just click the button that reads Fork in the top right of this page. Doing this will provide you with your copy. You'll need to change a few basic settings in your copy.

    Deploy to Heroku

    Make sure you Fork this repository before clicking the Deploy to Heroku button below

    Click the button below to deploy this app to the Heroku account you created earlier. Once complete, locate the URL of your app. You will need this for the following step.


    Once the app is deployed, you may want to connect your forked GitHub repository to your Heroku app for easy deployment. You can do this by navigating to the Deploy tab within your app on Heroku and following the instructions.

    Update Your App Settings in Your Forked Repository on GitHub

    Navigate to settings.js in your forked copy of the repository and change each of the four variables to the appropriate values. You can find your app's URL by opening your app or navigating to the Activity tab in Heroku and scrolling to the middle of the page to the domains section. See the example below.

    exports.url = '';
    exports.senderEmail = "";
    exports.senderName = "Sender Name";
    // set 'exports.listId = null' to add contact to all contacts, but no specific list
    exports.listID = 651138;
    // set 'exports.templateId = null' to opt out of using a template
    exports.templateId = "dbc810ec-b776-4345-b0c7-02e2bbcd2ab4"

    Add Contact to a Custom Marketing List (Optional)

    By default, the widget is configured to save a new contact to your main list of ALL CONTACTS. However, you may choose to save new contacts to a specified custom list as well. To do so, you must first create a new contact list by navigating to Marketing Campaigns -> Contacts, and then click the blue button in the top right corner of the page. Once the list is created, you will require the list ID. You can find this number by navigating to the list and looking at the URL. The list ID will be the numbers following the last forward slash. For example, the list ID of a list with URL of would be 651138. Once you have created a new list, change the value of exports.listId to the ID of that marketing list. This value is null by default.

    Use a Transactional Template (Optional)

    You may also send your confirmation email using transactional email templates to give your email a more professional look and feel. To do so, you must first create a template by following the steps provided in this guide. Once you have created a custom transactional email template, change the value of the exports.templateId to the ID of the template you created. If you choose to use templates, you must include a substitution tag named "link_insert". This will be substituted with the link that signs up a user in the double opt-in process. (Example template below)

    alt text

    Edit the Form with Your Custom URL

    Navigate to the index.html file (server -> static -> index.html) and change the action in the form to reflect your app's URL. Remember to leave "/confirmEmail" at the end. The text in this file is what you will embed in your website. See below for an example.

    <form action="" method="post">
    		<legend>Enter Your Information</legend>
    		<label for="email">Email:</label>
    		<input type="text" name="email" placeholder="" /><br>
    		<label for="first_name">First Name:</label>		
    		<input type="text" name="first_name" placeholder="John" /><br>
    		<label for="last_name">Last Name:</label>
    		<input type="text" name="last_name" placeholder="Doe" /><br>
    		<button type="submit" value="Submit" />SIGN UP</button>

    Remember to always re-deploy your app after making any changes.

    Add API Key as Environmental Variable on Heroku

    Next, configure your API key as an environmental variable, which can be done either through Heroku's user interface or the Heroku CLI as shown in these directions. Updating the environment variable in your Heroku account can be done by logging into your Heroku account, navigate to your newly deployed app, and clicking settings. Inside the settings page, you will see an option to "Reveal Config Vars". You must name your variable holding your API key SG_API_KEY.

    Enable Event Webhook

    The final step is to enable the event webhook on your Twilio SendGrid account. This will allow the opt-in component of the signup to function correctly. To set up an event webhook, navigate to Settings -> Mail Settings, and then click on Event Notification.

    Make sure the toggle in the top left of that section is set to ON. Click edit. Enter the root URL of your Heroku app + '/signup'. The following is an example URL:

    For the types of events to receive, make sure to select only Clicked. Then, click the blue checkbox in the top right corner of the section to save changes.

    Test Your Widget

    To quickly test that your subscription widget is working correctly, you may navigate to the root URL of your Heroku app and enter an email that you have access to. If everything is working, you should receive an email with a link to confirm your subscription. Upon clicking this link, the email should be added to the Twilio SendGrid contact list you created earlier.

    Usage and Customization


    To use this widget, once you've followed the setup steps above, drop all of the text from the index.html file you altered earlier into any website.


    You may change the look and feel of the form or create a new one. The form will continue to work so long as the action is what you specified earlier, the method is a POST, and there is an input element with name email. The default widget comes with three fields: 1) email, 2) first name, 3) last name. You may remove first and/or last name if you so choose. Also, you may change the form's styling by adjusting the CSS contained in index.html.

    Adding New Fields

    You may also add custom fields to the form to save other information about your users during the sign up process. To do so, simply add an input field with the name(s) of your custom field(s). If you add a custom field to your form that does not already exist in your Twilio SendGrid account, one will automatically be created with the name specified in the form. The example below shows a form with the custom field "favorite_color".

    <form action="" method="post">
    		<legend>Enter Your Information</legend>
    		<label for="email">Email:</label>
    		<input type="text" name="email" placeholder="" /><br>
    		<label for="first_name">First Name:</label>		
    		<input type="text" name="first_name" placeholder="John" /><br>
    		<label for="last_name">Last Name:</label>
    		<input type="text" name="last_name" placeholder="Doe" /><br>
    		<label for="favorite_color">Favorite Color:</label>
    		<input type="text" name="favorite_color" placeholder="Blue" /><br>
    		<button type="submit" value="Submit" />SIGN UP</button>

    You may also change the look of the check-inbox.html and success.html files, both of which are located in the static folder with index.html. These are the pages that users will be directed to upon entering their email and clicking the confirmation link, respectively.

    Finally, you may change the content of the confirmation email by changing the mailText variable in the contact_list_controller.js file, which is located in the controllers folder. However, be sure to keep the link intact. If you choose to use a transactional email template, the template will produce the mail text, and you may ignore this step.

    mailText = "Thanks for signing up! Click <a href='" + url + "'>this link</a> \
    	to sign up!  This link will be active for 24 hours."




    npm i @sendgrid/subscription-widget

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