What are email headers?

Email headers are metadata lines attached to every email recording the full path from sender to recipient, including a timestamp at each server handoff.

Why is my email delayed?

Common causes: spam filtering queues, overloaded relay servers, corporate mail gateway policy holds, greylisting, and DNS resolution failures.

How do I find raw email headers in Gmail?

Open the email, click the three-dot menu in the top-right corner, select Show original, then copy all the text.

How do I find raw email headers in Outlook?

In Outlook on the web: open the email, click (...) then View then View message source. In Outlook desktop: open the email, click File then Properties, copy the Internet headers box.

Is my email data private?

Yes. WhyIsMyEmailLate runs entirely in your browser. No email header data is transmitted to any server or stored.

Are the delay readings accurate?

Delay readings are calculated from timestamps recorded by individual mail servers and are not independently verified. Server clock skew or MTA misconfiguration may cause inaccurate readings. Results are for diagnostic reference only.

Free · No sign-up · 100% private · Runs in your browser

Why Is My Email Late?

Paste raw email headers below, then click Analyze Headers to trace every server hop, calculate transit delays hop-by-hop, and pinpoint exactly where time was lost — alongside a plain narrative of the delay, useful for anyone from IT administrators to business users trying to understand why an important email never arrived.

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How to Use This Tool

Email headers are the hidden audit trail every message carries — a timestamped log of every server that touched your email before it reached the inbox. When a message arrives hours late, gets flagged as spam, or disappears entirely, those headers contain the answer.

To get started, open the original message in your email client. In Gmail, click the three-dot menu and choose Show original. In Outlook, open the message properties dialog. In Apple Mail, use View → Message → All Headers. Copy the entire raw header block — everything from Return-Path: down to the first blank line — and paste it into the box below.

This tool runs entirely in your browser. No header text leaves your device. Sensitive addresses are masked by default before any copy or export action.

Paste Raw Email Headers0.0 KB / 200 KB

No server. No storage. No tracking. Headers never leave your browser.

Get a Shareable Executive Report

After analyzing your headers, download a plain-English summary your manager, legal team, or vendor can read immediately — no IT background needed. Unlike any other email header tool.

How to copy raw email headers

Understanding Email Headers and Delivery Delays

Every email you send travels through a chain of mail servers before reaching its destination. Each server in that chain — called a Mail Transfer Agent, or MTA — appends a Received: header recording when it accepted and forwarded the message. By reading these headers in sequence, it is possible to calculate exactly how long each server took to process and hand off the email, and to pinpoint the precise step where significant time was lost.

Email delays are more common than most people realize, and they rarely mean the message is lost. The most frequent causes include greylisting (a spam-prevention technique where the receiving server temporarily rejects the first delivery attempt, causing a 5–15 minute retry gap), outbound queue backlogs (the sending server was under load and held the message before dispatching it), and corporate gateway policy holds (compliance systems that inspect content before allowing it to leave the organization). Less common causes include DNS lookup failures, TLS negotiation issues, and recipient-side rate limiting by large providers such as Gmail or Outlook.

WhyIsMyEmailLate parses the raw header block, normalizes every timestamp to UTC to eliminate timezone inconsistencies, and calculates the inter-hop latency at each step. The result is a hop-by-hop timeline that visually identifies the bottleneck — the single server responsible for the largest portion of the delay. A plain-language Transit Narrative then translates the technical findings into a clear explanation suitable for anyone from IT administrators to business professionals trying to understand why an important message arrived late.

All processing runs entirely in your browser. No headers, email addresses, or IP addresses are transmitted to any external server. The optional PII masking feature further redacts personal identifiers from the displayed output, making it safe to share analysis results with colleagues or IT teams without exposing sensitive routing data.

Diagram: three Received lines from an email header turned into a timeline, showing a 33 minute gap between the outbound relay and the recipient's server — The analyzer reads Received lines from the bottom up and measures the time between each pair of servers.

Four steps for finding a delay: start at the bottom Received line, convert to UTC, subtract neighbouring times, and name the server before the largest gap. — The method behind the timeline: the largest gap points at the server that held the message.

A reply starting with 2 means accepted, 4 means temporary so the sender retries, and 5 means permanent so the message bounces. — Why some delays are deliberate: a 4xx reply makes the sender wait and retry.

From the Learning Center

Guides on reading headers, authentication results, SMTP error codes and the real causes of delay.