I would like to request a feature or functionality so that we can specify or have MailPoet use images from their original uploaded source file (such as JPG or PNG) instead of any versions that have been modified by image optimization plugins (such as conversion to WebP format).
The problem that I've noticed is that when the email creator is placing images in the email designer, if they place the image from the media folder and that image has been converted to the WebP format, that is what gets used by MailPoet. This displays without any problems in the web browser, but many email applications (such as Outlook, for example), do not correctly display the WebP image format and so the images show up as broken or missing.
However, if the email creator manually goes into the WordPress media folder and then copies the path to the ORIGINAL image that was uploaded (typically in JPG or PNG formats), if they paste that URL path into the email template, it will pull the appropriate image format that will be displayed properly in all email applications.
So, there is a method to overcome this issue by manually selecting the source path. However, most people are not going to know how to do this or might not understand why their images are displaying when they create the emails, but then appear broken when viewed by their subscribers. It also creates additional technical steps the user has to do for each image that is added to the email. If there was a way for MailPoet to automatically identify and reference the compatible image formats (JPG, PNG, and GIF), that would be a fantastic feature and likely reduce a lot of problems. We need those next-generation image formats like WebP for the benefits they provide to our websites, but they cannot be used for the emails that get sent out to subscribers.