How do SPAMMERS make e mails look like they have come from a real users e mail account?

Question

i.e. [e-mail]

also sometimes at work i get SPAMS from an unknown e mail user at the same domain i am in???? also usually If we get sent an e mail to our domain but the user doesnt exist our ISP usually automatically creates a bounce back to the sender but the SPAMS are getting through - how does the SPAMMER do this?????

please help......v frustrating!

cheers wikipedia page is interesting but doesnt explain how its done and how i can prevent it from happening.

The ISP would automatically bounce back from the senders address which is in the e mail isnt it? there must be extra security tools or features of windows 2000 exchange server which can be configured to help this situation?

arminatorx - yes so i can create a bogus e mail address and send an e mail out? i dont see what this proves? i want to know how an email sent into my work for a particular recipient who doesnt exist is delivered? also how can spammers send from domains that other people own?

Answer 1

http://en.wikipedia.org/wiki/Spoofing_attack
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Answer 2

The ISP cannot return to sender if it does not know who the sender is. It's really easy to change the reply address on an email sent via outlook or a mail command in php asp etc. The spammers can also use your own mail server to send emails you will need to make sure the proper security is taken to prevent this happening.

Answer 3

I'm not too sure mate but I know a way.

I used to do PHP coding and you can use a function called mail. You can easily setup this to show any email address you want to be seen by using a variable like $sendersemail = [e-mail];

Then you would simply use a CRON setup to run the script every few hours and they can easily make the variable of sendersemail change every time the script is started using a list etc.

That is the only way I can think of it being done, I did a mailing list for one of my websites and I would imagine most spammers do this or use bots or something to do there dirty work.

I don't know a way to find out the true email address but you can find the isp details using outlook somewhere. Hope this helps you anyhow.

Cheers
Paul

Answer 4

To show you how easy it is: Open your email program. Create a new email-account. Put in a fake email adress for you.

Now write an email with this account and send it to your real adress. You will see, that the sender has this faked adress that you entered.

This is, because most mail servers do not check outgoing mail if the sender is really a true adress.

Furthermore: Spammers don't use normal e-mail programs, where they enter their faked adress.
They have specialized programs, that automatically generate bogus adresses for each spam message that they send out.