Email Deliverability Doctor (Free Gateway)

The problem

Bad subject lines trigger spam filters and annoy recipients before they even open your email. Most developers guess at what works or use deceptive prefixes that damage sender reputation and trust.

What it does

• Identifies high-risk patterns like urgency framing, money-prize language, and clickbait gaps.
• Explains how specific phrases signal red flags to both automated filters and human readers.
• Generates two clean, honest rewrites focusing on directness and genuine curiosity.
• Performs a content-subject mismatch check to ensure the headline reflects the actual body.
• Flags deceptive tactics like fake RE: or FWD: prefixes that harm deliverability.

Why this beats prompting it yourself

Generic LLM prompts often suggest "catchy" titles that actually increase spam risk. This skill enforces strict honesty rules and uses a structured risk-assessment framework to prioritize long-term sender reputation over cheap clicks.

Use cases

• Reviewing cold outreach subject lines to remove filter-triggering urgency.
• Cleaning up newsletter headlines that sound too much like marketing hype.
• Verifying that a subject line accurately reflects the email body to prevent high bounce rates.
• Onboarding junior SDRs or marketers to help them understand deliverability best practices.

Known limitations

Does not provide numerical spam scores or guarantee inbox placement. It cannot fix deliverability issues caused by poor list quality or improper SPF/DKIM/DMARC setup.