Definition
A Received header is a trace line that each mail server adds as a message passes through. Reading the full chain shows the route a message took, the times at each hop, and where delivery stalled.
Received headers are the first place to look when diagnosing bounces, delays, and delivery problems, because they record the actual path and timing of the message.
Received headers trace every hop a message takes, making delivery failures diagnosable. Reading them bottom-up shows the route and timing. They are the first place to look when mail bounces or is delayed.
Reading Received Headers
Read Received headers from bottom to top to follow the delivery path.
Compare timestamps at each hop to find where delays occur.
Why It Matters
Received headers trace every hop a message takes, making delivery failures diagnosable. Understanding them is essential for debugging bounces and delays.
Best Practices
- Read Received headers from bottom to top to follow the path.
- Compare timestamps to find delivery delays.
- Use them to confirm authentication and relay changes.
- Check for signs of tampering or unusual hops.
- Reference them when diagnosing bounces.
Was this useful?
Related Glossary Terms
Abuse Complaint
An abuse complaint is a report from a recipient who marks an email as spam, which negatively affects sender reputation and deliverability.
Alt Text
Alt text is the written alternative to an image in an email, displayed when images are blocked, slow to load, or consumed by screen readers.
AOL Mail for Email Marketers
AOL Mail is a legacy email provider with specific deliverability requirements and rendering quirks, now operating as part of the Yahoo+AOL network under shared infrastructure.
Email Authentication Protocols
Email authentication protocols are technical standards that verify the identity of an email sender, helping mailbox providers distinguish legitimate mail from spam and phishing.
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.
Frequently Asked Questions
A hop-by-hop trace added by mail systems as a message routes. Received headers trace every hop a message takes, making delivery failures diagnosable.
The oldest hop is at the bottom; the newest is at the top. Reading them bottom-up shows the route and timing.
Yes, they reveal where and why delivery stalls. They are the first place to look when mail bounces or is delayed.
One for each server the message passes through. Received headers trace every hop a message takes, making delivery failures diagnosable.
When each hop processed the message. Reading them bottom-up shows the route and timing.