Question: Can email be "Returned to Sender?" Jo-Ann Duncan <jo-ann@quibble.com> wonders what happens to email that's addressed incorrectly. "I sent mail to a friend, and then thought perhaps she had changed her email address when I didn't hear back from her. If I send mail to someone with the wrong address does the message get lost in transit or does it come back to my computer in some way?"

Answer: In most cases, you should receive a message back, saying that your original message couldn't be delivered. In Internet terms, this is called a "bounce," and mail that comes back to you is said to have "bounced." The most common reason for a message to bounce is human error - you type the address slightly wrong. Computers are utterly literal, and if you send email to <aec@netbits.net> instead of <ace@netbits.net>, my mail server will bounce it back to you, since, unlike your friendly local postal employee, it can't figure out what you mean.

(If you don't receive a message back, it's conceivable that it has disappeared into the ether, but it's more likely that your friend simply hasn't gotten around to responding yet.)

There are two common types of bounces, "User unknown" and "Host unknown." Both are generally caused by mistakes in the recipient's email address, but "User unknown" bounces occur when you make a mistake in the username portion of the email address (the part before the @) and "Host unknown" bounces generally occur when you make a mistake in the domain name portion of the email address (the part after the @). The best way to avoid mistakes in email addresses is to use the address book feature of your email program, where you can create a nickname like "Adam" that maps to <ace@netbits.net>. Then, as long as you type the nickname correctly, your email program will replace it with the proper email address.

The main thing you can do when you receive a bounce is to send the message again if the text of the original message has been included. Some email programs, like Qualcomm's Eudora, even have a Send Again command (look in the Message menu) that can resend a bounced message. Otherwise, if you save your outgoing messages (a good idea) you can copy and paste the original text into a new message, making sure to enter the email address correctly this time. Unfortunately, if you don't save outgoing messages and the original text isn't in the bounce, you'll have to retype the entire thing.

Some bounces aren't your fault. If an ISP is moving machines or generally mucking with setups, mail might bounce temporarily until they fix the problem. In that situation, wait a day or so and send the message again. You might also receive bounces telling you that there are temporary delivery problems but that the server will continue to attempt to deliver the message. If that's true, do nothing unless the message bounces for good because it's likely the problems will be resolved automatically. Finally, some people change their addresses fairly frequently without informing their friends and colleagues. If that's true, you can try to send the message to another email address if you have it (look in the signature of a previous message - many people have multiple email addresses), or try to find out the new address by asking a mutual acquaintance or calling the recipient on the phone. [ACE]