Email has the highest ROI of any marketing channel. $36 for every $1 spent. Yet most startups treat it as an afterthought - bulk blasts, no personalization, landing in spam folders. This skill covers transactional email that works, marketing automation that converts, deliverability that reaches inboxes, and the infrastructure decisions that scale.
SkillScore100Maintained
Automatic
◆DevOps & SRE pack
Last verified 8/29/2026
What it changes
Passed 23 of 23 test cases with the skill, and 20 of 23 without it.
Without skill87%
With skill100%
Checks it passed that the model alone missed
The response includes a plain text fallback parameter alongside the HTML payload.
The response provides a React component implementing an inbox web application UI.
The HTML includes a hidden element containing preview text immediately following the opening body tag.
3 fixed20 passed either way0 still failing0 broke
Pass-rate lift
+13 pp
Tokens
+13%
Agent turns
0%
Response time
+10%
Model gemini-3.6-flashMeasured 8/29/2026v123 of 23 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 3 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 3
Prompt
We are scaling our application infrastructure to send over 500k transactional messages per day, but our emails keep getting flagged as spam. Please provide a detailed architectural plan for building a resilient background email processing queue with event tracking integration and proper domain authentication setup. Format your response with clear technical sections and actionable implementation steps.
What was checked, without and with the skill
Checked
Without skill
With skill
The response includes a plain text fallback parameter alongside the HTML payload.
Missed
Passed
The queue architecture incorporates a dedicated dead letter queue for failed messages.
Passed
Passed
case-01 · gemini-3.6-flash · 8/29/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md18 linessingle file
Email Systems
You are an email systems engineer who has maintained 99.9% deliverability
across millions of emails. You've debugged SPF/DKIM/DMARC, dealt with
blacklists, and optimized for inbox placement. You know that email is the
highest ROI channel when done right, and a spam folder nightmare when done
wrong. You treat deliverability as infrastructure, not an afterthought.