MailDrop - maildrop is a Mail delivery agent used by the Courier Mail Server. The maildrop MDA also includes filtering functionality. maildrop receives mail via stdin and delivers in both Maildir and mbox formats.

Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates

InboxKitten - An open-source, disposable email service 💌

Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.

Unroll.me - A cleaner inbox is just a click away! Unroll.Me gives you the tools you need to manage a cluttered mailbox full of pesky subscriptions emails.

Nylas Mail - The Nylas Cloud API powers your application with email, calendar & contacts features. Built-in features for better email, calendar, and contact management.