Offer ability to disable tracking pixel for legal privacy compliance
Follow-up plugin automatically adds a tracking pixel to each sent email. It basically tracks as soon as someone is opening the email.
This means, by default, anyone using this plugin who sends emails to eg EU citizens is at risk of facing fines.
You can read more about this in https://ec.europa.eu/justice/article-29/documentation/opinion-recommendation/files/2006/wp118_en.pdf in the section "V. OTHER EMAIL RELATED SERVICES".
There is a workaround to remove the filter that is adding the tracking pixel. However, it can easily break at any time should the filter be changed in any way.
I suggest you add a feature to disable this tracking pixel and maybe even have it disabled by default so people have a chance to check their legal situation, privacy notices and privacy policies before opting in to this.
Another downside is that some email providers are smart and detect tracking pixels meaning such mails are more likely to be classified as unimportant or may be even put into spam.