GlockApps vs Mailpit

GlockApps helps marketers and businesses check email deliverability and investigate placement problems before sending campaigns. Inbox Insight shows whether test messages reach inboxes, spam folders, or subfolders at different providers, and checks them against SpamAssassin, Barracuda, Microsoft Exchange Online Protection, Proofpoint, and a Google filter. Reputation tools check IPs and domains against blocklists and report sender scores and placement by IP. Content analysis covers message size, images, and links, with an HTML compatibility checker. DMARC Analytics collects reports, tracks sending sources, and retains reports for a year. Uptime Monitor checks IPs, SPF, DKIM, DMARC, HTTP, TLS, and TCP, with checks configurable as often as every minute. The API supports automated testing, result retrieval, and client management by projects and folders on all plans, including free. GlockApps runs on the web and through an API. Its free plan includes two spam test credits; paid plans start at $59 a month, billed annually at $708.

Mailpit is a free, open-source tool for checking email content and SMTP delivery without sending messages to real addresses. It runs a local SMTP server alongside a web interface and REST API, and is available for Linux, macOS, Windows, Docker, and self-hosted deployment. The interface displays formatted HTML, source, text, headers, raw messages, and MIME attachments with image thumbnails. Checks include HTML and link testing, message screenshots, and optional SpamAssassin scoring. The API can access, search, send, delete, tag, and release messages; messages can also be relayed, forwarded, or used to trigger configurable SMTP errors. Mailpit can send message-summary webhooks and offers a Cypress package for integration tests. The web UI and API can use HTTPS and basic authentication; SMTP supports optional authentication and TLS. By default, SMTP listens on port 1025 without encryption or authentication. Mailpit keeps the most recent 500 messages by default.