You can easily configure your email account to display email headers within your email.

Squirrelmail

1. Click on the email to open it

2. Click on View Full Header

Horde

1. Click on the email to open it

2. Click on Show All Headers

Apple Mail

1. Click on the email to open it

2. Go to the View menu, then select Message

3. Select Long Headers

Thunderbird

1. Click on the email to open it

2. In top left menu Click on View > Headers > All  

Outlook

1. Open the message

2. On the Message tab, in the Options group, click the Dialog Box Launcher

In the Message Options dialog box, the headers appear in the Internet headers box at the bottom.