Guerilla Mail is a simple idea with one purpose: to avoid spam. The idea is dead simple: go to the website, it gives you a random e-mail address that's good for one hour, and links to nothing else. Register for sites or whatever with it, and then never worry about it again. Although the web service is convenient, sometimes it's not everything you need. For those cases, one might want to look into using the Guerilla Mail API.
Rpost made its name in the compliance space through its Rpost API and core products: email proof, privacy, and electronic signatures. Rpost’s core offering won a customer list full of household names across many industries, both public and private (Whole Foods, AT&T, and Civpol to name a few). Rpost now aims to bring its compliance strategy to all internet transactions via RPost Cloud.