Mailtrap - Email Delivery Platform that delivers just in time. Great for businesses and individuals.
Mailinator - Any Inbox. Any Time.
FakeSMTP - FakeSMTP is a Free Fake SMTP Server with GUI for testing emails in applications easily.
Guerrilla Mail - Guerrilla Mail is a web-based app that provides a disposable and anonymous email address. Users of the service are not required to set up an account in order to send or receive emails.
MailCatcher - MailCatcher runs a super simple SMTP server which catches any message sent to it to display in a...
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.