Prospect.io and Mailshake are both email outreach platforms that help businesses grow their customer base. The main difference between them is in their automation capabilities. Prospect.io offers more sophisticated automation solutions such as automated follow-ups and email filtering. On the other hand, Mailshake does not offer any type of automation, but does offer personalization features such as customizing each email sent. Additionally, Prospect.io offers an integrations with Salesforce, while Mailshake does not. Finally, Prospect.io is more affordable than Mailshake, making it a more attractive choice for businesses looking to optimize their email outreach efforts.