How to Understand the Date and Time in Email Headers

Discover the location of the servers the email passed through

An email passes through several mail servers on its way to a recipient. Each server records the time and date in the email header. By reading the header, you can find out when the message was sent, as well as where and for how long it was delayed.

An Example of Date and Time Info

Date and time information in email headers typically looks like this:

Sat, 8 Jun 2019 11:45:15 −0500

Here's what each of these snippets means:

  • Sat: The day of the week, using its three-letter abbreviation.
  • 8 Jun 2019: The date with a three-letter abbreviation for the month.
  • 11:45:15: The time in hours, minutes, and seconds using a 24-hour clock.
  • -0500: The time zone offset, which is the difference between the time and Coordinated Universal Time (UTC) time. The value is preceded by a plus sign if the time is ahead (east) of UTC, or a minus sign if it's behind (west). In this example, the time is five hours west of UTC, which is the Eastern time zone in the U.S.

If the time zone offset value appears as zeroes only, the time zone is unknown.

Review Date and Time Information

In the email's header, look for lines beginning with Date and Received. Compare these areas to get an idea of how long the message took to arrive in your inbox.

Header and metadata information in an email

The process for showing an email's header is simple but varies slightly among email clients. For example, from an open Gmail message, click Show Original. In Outlook, go to File > Properties.

Deciphering Time Zones

The most difficult parts to understand are the time and time zone offset. To convert the time to your time zone, use a time zone calculator.

Some email clients, such as Outlook, provide an option to adjust the settings to show the time based on your time zone.

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