MailHog vs MailTester

MailHog is a free email testing tool for developers. Applications send mail to it over SMTP, after which users can inspect messages in a web interface or retrieve them through a JSON API. The interface displays plain text, HTML or source, supports encoded headers and updates in real time. The API can list, retrieve and delete messages, and download complete messages or individual MIME parts. Messages may also be released to real SMTP servers. MailHog supports ESMTP RFC5321, SMTP AUTH and PIPELINING, and includes a Chaos Monkey feature for failure testing. Storage defaults to memory, with MongoDB and Maildir also available. It can run from the command line, as a daemon, in Docker or on AWS Elastic Beanstalk. Its default SMTP and HTTP ports are 1025 and 8025. In-memory storage limits Elastic Beanstalk deployments to one instance; load-balanced deployments require MongoDB-backed storage. MailHog is released under the MIT license.

MailTester checks why email may reach spam and returns a deliverability score out of 10. To run a test, generate a disposable address, send the message there and receive a report in seconds. Scoring starts at 10, subtracts points for detected issues, and explains penalties with suggested fixes. Authentication checks include SPF, DKIM, DMARC, domain alignment, reverse DNS and forward-confirmed reverse DNS. Sending IPs are checked against Spamhaus, SpamCop, Barracuda and other DNS blocklists. Content analysis covers HTML, text-to-image ratio, links, subject, List-Unsubscribe and Message-ID. Rspamd supplies a spam score and triggered rules. Newsletter checks include one-click List-Unsubscribe under RFC 8058, message size and text-image ratio. MailTester offers web, API and self-hosted platforms. Its API creates test addresses and reads report status and scores as JSON. The free plan costs nothing, needs no account and provides 25+ checks per test.