Every week I receive hundreds of unsolicited e-mails saying ‘Returned mail’ from unfamiliar addresses, and the sender is marked as MAILER-DAEMON@… The computer is protected using Spyware Doctor and Norton Antivirus but the problem still persists. The computer is running Windows XP Home.

What is happening is someone who is sending unsolicited email (spam) has acquired your email address and is using your email address as the ‘From’ address in the spam emails they are sending. This is called ’spoofing’ the sender of an email message. However, some of the addresses to which the spammer sends emails are not valid, and therefore the emails are bouncing. This means the mail server is sending a ‘Returned mail’ message in response. As the spammer has used your email address as the sender (in the email ‘From’ field) you receive the bounce-back messages. This is why you are receiving numerous emails with the subject ‘Returned mail’ from the address MAILER-DAEMON (this is the technical term for a mail server). As you may have guessed, this entire process is out of your control. You have no way to prevent someone from spoofing your email address and sending emails like they came from your account, and you cannot prevent the bounce-back messages from being sent to your email address. While you could change your email address to resolve this instance of the problem, it could reoccur with your new email address. That said, it is relatively unlikely if you are careful to whom you give your email address. So, changing your email address might be a good way to resolve this issue. To do this, you will need to speak with your ISP.

Should you not wish to change your email address, or the problem reoccurs with the new address, while we can’t prevent these bounce-back emails being sent, we can deal with the messages a bit better. By configuring a mail filter in your email client, you can automatically move such bounce-back messages to a particular folder in your email client so they don’t clog up your Inbox. Assuming you are using Outlook Express, first you need to create a new folder which will have these bounce-back messages. In the left-hand ‘Folders’ pane, right-click on ‘Local Folders’ and select ‘New Folder’. Name the folder ‘Spam’ and click OK. Next, go to the ‘Tools’ menu > ‘Message Rules’ > ‘Mail’. The ‘New Mail Rule’ window should appear. Here, we will specify what criteria should be used to move a message to the ‘Spam’ folder. So, we need to identify a criteria which is common to all the bounce-back messages, but not to a legitimate message. Probably the best criteria will be the subject line containing the text ‘Returned Mail’. Therefore, for the condition tick ‘Where the Subject line contains specific words’. For the action, tick ‘Move it to the specified folder’. You will see the rule has been built in the rule description. You will also notice that ‘contain specific words’ and ’specified [folder]‘ are in blue text. This allows us to specify the words and folder for the condition. Click ‘contains specific words’. Type ‘returned mail’ and then click ‘Add’. The text is now part of the rule description. Then, click ’specified’. Select the ‘Spam’ folder and click OK. The rule description should now read ‘Apply this rule after the message arrives. Where the Subject line contains ‘returned mail’. Move it to the Spam folder’. Give the rule a name (e.g. ‘Spam Bounce-Back Filter’) and click OK. You should now be presented with the ‘Message Rules’ window. Make sure the rule is ticked (enabled) and click OK. The bounce-back messages will now all be moved to the Spam folder.

There is one potential fault in this setup - should you send an email to an incorrect or invalid email address, you will receive a ‘Returned mail’ message for that email. Thus, the filter will move this to the ‘Spam’ folder, despite the fact it is a legitimate bounce-back. Therefore, I strongly recommend you regularly check (at least once a week) and clean-out the Spam folder in case any legitimate bounce-back messages have found their way into the folder.