MailPoet and Mailshake are both email marketing platforms that businesses use to send newsletters and campaigns. The main difference between the two is that MailPoet is more geared towards WordPress users, as it is a plugin that is integrated within WordPress, making it easier for businesses to create and manage email campaigns, without having to install any software. Mailshake, on the other hand, is a standalone application that is not specific to any platform and can be used with any other software. It also provides more advanced features, such as email list segmentation, A/B testing, and automated follow-up emails. Both services offer comprehensive reporting and analytics, but MailPoet comes with limited templates, while Mailshake provides a wide range of professional templates to choose from.