Helping people with computers... one answer at a time.

Sending truly anonymous email can be tricky, and just about any piece of semi-consistent data can be used to ID you, often including your machine name.

About sending anonymous email. You say "step one use someone else's computer...or public library computers." Question: why use someone else's computer? Why not to take a laptop to an internet cafe, create fake account there, send an email, and then later check responses not from home? Do PCs, laptops have a unique ID?

Computers don't really have a unique ID that would make it into your outgoing email.

However.

Email headers sometimes contain a lot of information that, when examined, or used with other information, can often result in some surprising deductions.

Like "Oh, it must've been Leo that sent that email!"

First, I need to clarify something.

There's proof and then there's proof.

Much of the information that I'm thinking of can relatively easily be spoofed or faked by someone with sufficient technical knowledge. The net result is that someone who knows what they're doing can do a pretty good job of hiding where email comes from.

"I believe that you're more at risk from an accumulation of information that, when analyzed, points back to you."

Heck, spammers do it every day.

So while some data might lead to some interesting conclusions, it's not by any means proof of a technical sort.

But sometimes it doesn't need to be absolute proof to cause a problem.

The piece of information that I'm most concerned about in this scenario is your machine name - a name you choose when you first installed or configured Windows. You can see yours by looking at the properties of "My Computer":

Windows 7 Computer Properties highlighting computer name

That's the name I assigned to my laptop computer.

Some, but not all, email programs will include that information in the headers of outgoing email. Some, but not all, network configurations will add that information to the routing information in the headers of outgoing email.

Here's an example of the network case, modified somewhat to obscure some irrelevant details:

Received: from NOTENXPS (xxx.xxx.xxx.xxx) by smtp.somerandomservice.com
 (xxx.xxx.xxx.xxx) with Microsoft SMTP Server id 8.1.311.2; Thu, 25 Mar 2010
 16:33:27 -0400

You can see that the actual name of the machine sending the email is right there for the recipient to see, if they know where to look.

Even taking your machine to another location may not change this information, and indeed may cause it to appear due to a different network configuration.

As I said, your machine name may not be included - it's not something you can count on - but it's also not something you can count on not being there either.

Now that's the most obvious, and of course you could change your machine name at will.

However.

It's just one piece of a larger puzzle. Perhaps an obvious piece, but just a piece.

I believe that you're more at risk from an accumulation of information that, when analyzed, points back to you. Even without a machine name, things like consistent (albeit untraceable) IP addresses, email programs, browser information, all the way down to writing styles and wording can - when gathered together - potentially paint a picture where you're the only likely result.

So depending on how paranoid you are about such matters and perhaps factoring in the "cost of discovery", should it happen, you may want to consider changing as much as possible.

Changing your machine is one of the easiest.

Article C4259 - April 14, 2010 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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6 Comments
vincent
April 14, 2010 8:42 AM

Shall I ask the obvious then...?
Why on earth would you want to send an email to someone, going out of your way to make sure the person on the other end can't find out who the email comes from?
I wonder...

Aside from illegitimate uses like harassment, the most common scenario for a completely legitimate need to send anonymous email are things like whistle-blowers - folks we need to be able to report information without fear of it adversely affecting their jobs, or worse.
Leo
17-Apr-2010

Mark
April 14, 2010 11:45 AM

A very interesting book to learn some good tricks is Little Brother by Cory Doctorow. The book is fiction but most of the technology is real. It's so real, that some of the technology which wasn't real at the time of writing is being worked on now, eg paranoid linux, which is now being put together to work like in the book. It's a fun read and you can learn a lot.

John
April 20, 2010 8:18 PM

Two words for wanting to send anonymous email:
Iran
China

Sandy Smith
April 21, 2010 6:55 PM

I don't much care about "anonymous email" but did find the tech spechs in your print screen impressive! ;)

Smile And that's just my laptop. My desktop is a quad-core.
Leo
23-Apr-2010

Greg Bulmash
April 22, 2010 8:30 AM

I'll second Sandy. 8 gigs of RAM and a T9600 CPU in your laptop. Sweet.

Rick Muzaria
July 19, 2010 11:02 PM

well, can you do that if the sender uses gmail? I think you can't.

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