Marcus Webb

Marcus Webb is an Email Deliverability Specialist and Infrastructure Engineer who has spent more than a decade operating at the technical frontier of commercial email — the layer most sales teams never see but that determines whether their messages reach the inbox or vanish into spam. He began his career at an enterprise email service provider, where he engineered SMTP relay infrastructure processing over 200 million messages per day for Fortune 500 clients.

At Cruson, Marcus leads deliverability research and writes the technical guides that help SDR teams, growth marketers, and agency operators understand the invisible infrastructure underneath their cold email campaigns. He believes that most bounce rate problems, spam folder placements, and domain blacklistings are not bad luck — they are the predictable result of skipping a handful of DNS configuration steps that take less than 20 minutes to fix.

Marcus specializes in the full deliverability stack: SPF, DKIM, and DMARC record auditing, MX record hierarchy analysis, real-time SMTP handshake verification, catch-all domain detection, spam trap identification, and domain warming schedules. He has audited the deliverability infrastructure of over 800 companies and helped reduce average industry bounce rates from 8.4% to under 1.5% across his client base.

Marcus also contributes to open-source SMTP diagnostic tooling and writes a widely-read technical newsletter on email infrastructure best practices, read by deliverability engineers at major ESPs worldwide.