Mailscribe

Mailscribe is a free web hub of email marketing tools and guides for individual email marketers, small business owners, and marketing pros who want quick help with planning, copy, and deliverability.

Key capabilities include:

• Subject Line Generator to produce subject line ideas in seconds for upcoming campaigns
• Email Verifier for quick email address checks to help reduce bounces before sending
• SMTP Tester to test SMTP connectivity, TLS, and authentication to troubleshoot sending setup
• Campaign planning and deliverability guidance, including checklists and practical articles

Pricing: Free.

What makes it notable: it runs without signups, stays ad-free, and takes a privacy-first approach (it states it does not store prompts, generated results, or checked email addresses, with most state kept in the browser), making it well-suited for fast, no-commitment troubleshooting and pre-send checks.