Definition
Email delivery path analysis traces an email's journey from the sending server through the internet infrastructure to the recipient's inbox. The path includes the sender's SMTP server, any intermediate relay servers, DNS lookups for MX records, the recipient's incoming mail server, spam filtering engines, authentication checks, and final delivery to the inbox, spam folder, or rejection. Analysing the delivery path helps diagnose where and why deliverability failures occur.
Key Stages in the Path
- Submission — email is handed from the ESP to the sending MTA
- DNS resolution — sender domain and recipient domain DNS lookups
- Connection and authentication — SMTP handshake, SPF and DKIM verification
- Routing — email passes through intermediate MTAs and gateways
- Filtering — recipient's spam filter evaluates the message
- Delivery — email is placed in inbox, spam, or rejected
Best Practices
- Use email delivery logging tools to capture delivery path data for every send
- Investigate delivery path anomalies when inbox placement drops for a specific ISP
- Compare delivery paths across ISPs to identify where routing differs
- Document normal delivery path timing so deviations are detectable
- Use DMARC reporting to validate authentication delivery path integrity
Related Glossary Terms
BIMI
BIMI (Brand Indicators for Message Identification) is an email standard that allows brands to display their logo next to their emails in supported email clients. It requires DMARC enforcement at quarantine or reject policy.
Bounce Classification
Bounce classification uses SMTP codes (550, 551, 552, 553, 554, 450, 451, 452) and enhanced status codes to categorise permanent and transient delivery failures.
Email Deliverability
Email deliverability is the ability to land in the recipient's inbox rather than the spam folder. It depends on sender reputation, authentication, list quality, and content practices.
DMARC Alignment
DMARC identifier alignment determines whether the domain in the From header matches the domains used in SPF and DKIM authentication. Strict or relaxed.
Acceptance Rate
Acceptance rate is the percentage of emails submitted for delivery that are accepted by the recipient's mail server, representing the first deliverability checkpoint before inbox placement is determined.
Email Account Health Score
A composite metric that evaluates the overall health of an email sending programme based on deliverability, engagement, list quality, and compliance factors.