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A friend of mine got worried the other day - she received an email from her own address, with no subject. She thought somebody had gotten into her email account and sent the message from there, possibly using it to spam or otherwise attack her friends, too.
This is almost certainly not the case. Here's a short explanation of how it works:
Anybody can use any email address at all as the sender address when sending an email, just like anybody can write any return address they like on a piece of paper mail.
Here's the far longer explanation of how it works:
There are two places to specify the sender (and recipient) of an email. One is used by the mail server handling the mail, the other is what you see when you look at the mail in your mail client.
The one used by the mail server is called the "envelope sender" (and "envelope recipient"). If you compare it to a paper mail, it's what it sounds like - it's the sender/return address (and recipient address) that is written on the outside of the envelope. They are usually, but not always, the same address that you will see in when you look at the actual piece of mail. Again, compare to a paper mail - it's entirely possible to send a paper with somebody else's address, but then put it in an envelope with your address on it. Then the paper will be delivered to you, but when you open the envelope and look at the actual piece of mail, you see that it's not your name on the paper. The difference is that with email, you usually don't see the envelope unless you tell your email client to show it to you. (How you do that will of course depend on what email client you're using.)
This is almost certainly not the case. Here's a short explanation of how it works:
Anybody can use any email address at all as the sender address when sending an email, just like anybody can write any return address they like on a piece of paper mail.
Here's the far longer explanation of how it works:
There are two places to specify the sender (and recipient) of an email. One is used by the mail server handling the mail, the other is what you see when you look at the mail in your mail client.
The one used by the mail server is called the "envelope sender" (and "envelope recipient"). If you compare it to a paper mail, it's what it sounds like - it's the sender/return address (and recipient address) that is written on the outside of the envelope. They are usually, but not always, the same address that you will see in when you look at the actual piece of mail. Again, compare to a paper mail - it's entirely possible to send a paper with somebody else's address, but then put it in an envelope with your address on it. Then the paper will be delivered to you, but when you open the envelope and look at the actual piece of mail, you see that it's not your name on the paper. The difference is that with email, you usually don't see the envelope unless you tell your email client to show it to you. (How you do that will of course depend on what email client you're using.)
