Customize the Confirmation Email Subject and Content
For customizing the confirmation email subject and content, you can choose between using the standard MailPoet visual email editor, or a simplified text editor that you can customize with shortcodes.
If you check the "Enable visual subscription confirmation emails" option, then you can open the template editor and customize your email in the visual editor:
Alternatively, if you leave that setting disabled, you can customize the subject and content of the confirmation email directly in the settings page.
The shortcode used to confirm the subscription is [activation_link] [/activation_link]
When users click on this link, their subscription will be confirmed. It's not possible to edit this shortcode or use a different link, but you can change the link text by changing the content in the shortcode.
There are several other shortcodes that can also be used to customize the content (listed along the side of the editor textbox), such as the subscriber's first and last name.
This is how the default signup confirmation email should look:
You can customize your signup confirmation email with HTML code as described here. However, note that it's risky to customize it too much. As this is the first email that will be sent to the subscriber, it's important to reduce the chances of it landing in the Spam folder. So if you have images and custom HTML, it increases the chances of causing deliverability problems.