GreenMail vs MailHog
No leader: the top candidate GreenMail has only 0.31 confidence (low), below the 0.35 needed to declare a winner. The attribute-by-attribute breakdown below, with a source and date on every value, is the honest way to compare them.
Capabilities
Feature-by-feature on the axes that matter for email testing dev. “-” means undocumented, not absent.
What each one is
The product in its own terms, so the numbers below have context.
GreenMail
A testing framework that emulates email server behavior (SMTP, POP3, IMAP) to help developers verify email functionality in their applications during testing, without requiring actual email infrastructure or sending real messages.
MailHog
MailHog intercepts and stores SMTP messages during development, providing a web UI and JSON API for viewing and managing test emails, with the option to forward messages to real mail servers.
Pricing
List pricing as published by each vendor, with the date we read it. Always verify at the source before you buy.
MailHog
Pricing not documented yet.
Platform & deployment
Where each product runs and how it can be hosted. A dash means undocumented, not unsupported.
Comparison generated from independently-sourced facts. Every value links to its source and retrieval date. See the method.