Send your issue to a test address and see where it landed at twelve mailbox providers, inbox or spam. The same report runs 42 technical checks on the copy that arrived: SPF, DKIM and DMARC alignment, blocklists, two spam engines, the Gmail and Yahoo bulk sender rules, and the content itself. Every problem comes with a plain-language fix. Free, no signup, with an API and an MCP server if you want to test from a script or an AI agent.
Quibr is an AI social media agent for newsletter creators. When a new edition goes out, it writes posts for X, LinkedIn, Threads and Facebook from it, in your own voice, spreads them across the week and publishes them. Approve every post, step in during an approval window, or let it run on its own. Works with beehiiv, Substack, Ghost, Kit, Mailchimp and any RSS feed. $29 a month, with a seven-day free trial. Formerly Letterly.
Price Comparison
Quibr starts at $29.
Feature Comparison
Email Spam Tester and Quibr both have great feature sets so the right tool for you really depends on your needs.
| Features | Email Spam Tester | Quibr |
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