Understanding Email Headers

Everyone knows how to send and receive emails but only a few understand the concept behind the process.
What is actually happening when you click on the send button?
Emails are not sent directly from your machine to the recipient's computer. Mail servers that are setup by your ISP or the email provider you are using for instance process incoming emails and transfer them to their destination.
The information are stored in email headers so that mail servers know where to transfer the mails to. This is very similar to how the local post office handles your postcards. They look on the cover to find out where the letter needs to be sent to.
Why postcards? Because all email contents are readable unless you use some form of encryption. If you do not, and the majority of Internet users does not, your emails are readable by every server and everyone listening in as they pass through on their way to the destination.
Email headers can help you a lot, especially when it comes to spam and malicious emails that you may receive in your email inbox. The concept is similar to regular letters. Just like it is possible to write any sender address and name on envelopes or postcards, it is possible to do the same for email recipient addresses.
The article "reading email headers - all about email headers" gives you an in depth overview about email headers.
Everything is explained with examples which makes it easy to follow through, even for people who lack the tech background. It begins with an introduction that explains "where mail comes from" and details "mail protocols" thereafter. The final part consists of a list of common mail headers which is great if you want to understand a certain part of the header.
Update: The guide is divided into four chapters. Displaying email headers explains how you display email headers in popular email clients such as Outlook, Netscape or Eudora. Please note that the article has been written in a time where popular clients like Thunderbird have not been created yet.
Received headers detail the emails origin and the route it took to get to you. These information are displayed in reverse order which means that the last received header in the email is in fact the first that received the email, and the first in the listing is usually the mail server of the email provider.
The last received header details what you can find out about the first server that processed the email. This can be helpful to identify the origin of the email which in turn can be used to report an email as spam or malicious.
Other headers finally lists other common email headers that you may come upon in emails.
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You said that Outlook isn’t your main email client, so which is your main one?
I think its thunderbird
It is Mozilla Thunderbird.
Awesome! This actually solved my problem… what a stupid bug.
If this is the same bug that I’ve encountered, there may be another fix: (1) hover over open Outlook item in Taskbar, cursor up to hover over Outlook window item, and right-click; (2) this should give you Restore / Move / Size / Minimize / Maximize — choose Move or Size; (3) use your cursor keys, going arbitrarily N/S/E/W, to try to move or size the Outlook window back into view. Basically, the app behaves as though it were open in a 0x0 window, or at a location that’s offscreen, and this will frequently work to resize and/or move the window. Don’t forget to close while resized/moved, so that Outlook remembers the size/position for next time.
THANK YOU Claude!!! I could get the main window to launch but could not get any other message window to show on the desktop. You are my hero!!!!
Solved my issue! 6 years later and this is still problem…
Fantastic. Thank you. Size did the trick.
This solved my Outlook problem, too. Thank you. :)
Thank you so much, this started happening to me today and was causing big problems. You are a life saver, I hope I can help you in some way some day.
You are a god – thank you!
thanks a lot…. work like charm.. :-)
Yah…thanks Claude. I’ve been having the same problem and tried all the suggestions…your solution was the answer. It had resized itself to a 0/0 box. Cheers
Excellent post. This had me baffled even trying to accurately describe the problem. This fixed it for me.
Thank you
Thanks a lot for the article. Don’t know why it happenend, don’t know how it got fixed, but it was really annoying and now it works :-)
Thanks a lot. I was facing this issue from past 3 week. I tried everything but no resolution. The issue was happening intermittently and mainly when I was changing the display of screen ( as i use 2 monitors). The only option i had was to do system restore. But thanks to you.
I’ve been tried to sole this problem for 12hours. Your comment about changing the display of screen helped me a lot!! Thanks!!
Thank you…don’t know why this happened but your instructions helped me fix it. Running Windows 10 and office pro 2007
Great tip! Thanks!
Worked for me, too – thank you!!!
It’s Worked for me, too
thank you very much!
I had a similar issue with Outlook 2013 on Windows 10 and this helped me to fix it. Thank you very much!
Thank you so much. Solved!
Considering you published this in 2012, incredible not been debugged by Microsoft.
Thank you again. M
This problem was faced by only one user logging to TS 2008 r2 using outlook 2010.The issue was resolved.
Thanks.
Great tip. Thank you!!!! If it helps, I had to use the Control Key and the arrow keys at the same time to bring my window back into view. Worked like a charm.
Thank you, this worked !!!!
Man, you are a fucking god. Thanks a lot, what an annoying bug!!
Awesome, this post solved the issue. Many thanks!