It is not mandatory to include this feature, but it is recommended to improve the user experience in the email. 'Open email in browser' is an alternative viewing option that we see as valuable. If a recipient is unable to read the email, or if the email contains broken image links, it can result in a bad experience for the customer and lead to them unsubscribing. It is therefore essential to include a clear link that encourages opening the email in the browser.

Considering that 43% of all email openings occur on a mobile device, it is particularly important to offer consumers alternative viewing options, especially for those who are unsure how to adjust their inbox settings to ensure correct display of links and images.