Details below are from Mailpit’s site and README on 17 October 2026. Check them for current details.
At a glance
| Proxy Mail QA | Mailpit | |
|---|---|---|
| Where it runs | Hosted: real addresses on the internet | Yourself: a single binary or Docker image, on your machine or in CI |
| How mail gets in | Sent to a real address by any app or service | Your app sends to Mailpit’s SMTP server (port 1025 by default) |
| Cost | Free plan, whole product under fair use | Free and open source (MIT) |
| Reading mail | Web app, REST API, npm package, Python helper, MCP server | Web UI (port 8025 by default) and REST API |
| Codes and links | Pulled out and shown on the account’s row, returned on their own by the API | Not pulled out: you read the message |
| Email checks | SPF, DKIM, DMARC, links to localhost or plain http, where links go, stated expiry, size, phone layout | HTML and CSS support, link check, SpamAssassin score |
| Kept | The address lifetime you pick, up to 30 days on the Free plan | The newest 500 messages by default |
| Works offline | No | Yes |
MailHog works the same way, on the same default ports, but Mailpit’s README notes it hasn’t seen active development or security updates for a few years.
Where Mailpit is the better choice
- Local development and CI service containers. Free, offline, no account, no limits beyond your machine: start it next to your app and every email lands in a local web UI.
- Checking your own templates. HTML and CSS support checks, a link check and a spam score, on every message your app sends.
Where Proxy Mail QA is the better choice
- Staging and preview deploys. Email goes out over the internet there, often through a real provider, so a catcher on localhost never sees it. A real address does.
- Hosted auth services. Supabase, Clerk, Auth0 and Firebase send from their own servers; a Proxy Mail QA address receives their emails without changing your app.
- What only real delivery shows. An email provider still in sandbox mode, missing SPF or DKIM, a link that points to localhost on staging.
- Many test accounts, shared. Personas, saved passwords, notes and every email per address, for the whole team, plus an MCP server for coding agents.