Spam Prevention Tips #5
If you are a webmaster or manage your own domain, one of the easiest things you can do quickly and cost effectively to reduce spam, is to stop using catchall email forwarding on your domain. Catchall mailboxes receive such high volumes of spam for two reasons;
1) Spammers take guesses at email addresses on your domain. They use dictionaries to prepend any word or name to your domain name as well as other methods where they employ clever tools to guess at other possibilities such as james.smith@yourdomain.com or jsmith@yourdomain.com. These tools can also generate countless other variations of an email address before then sending several thousand spam emails to your email server.
2) They also send spam messages to other people supposedly from guessed mailboxes on your domain. When these messages are bounced they end up coming back to your domain and if you keep catchall forwarding on, they ultimately arrive in your inbox. This technique is one of several forms of ‘backscatter`, a phenomenon which has been annoying and puzzling many email account owners for years.
Of course, the address the spammer tried to send a message to was probably also an invalid address, so this server may also bounce back the message, ensuring that the message continues to loop around causing endless backscatter. You can considerably reduce the amount of spam you receive by disabling catchall forwarding and thereby only receiving email sent directly to the addresses you have setup on your domain. A message sent to an address which you haven’t expressly setup is returned to the sender advising them that the address does not exist.
This is the correct functionality and prevents the increase and spread of spam.
