Packet Rat: Rat rolls his own version of an e-mailer ID

The Rat

Michael J. Bechetti

Few things jar the Rat's concentration worse than a ringing telephone'especially when there are plenty of hands available to answer it. 'Will somebody stop that abominable noise,' he shouted from his lair one recent morning, having just soldered his fingers together. The household landline rang a fifth time.

'It's a telemarketer,' his wife shouted back. 'Name Blocked, Num Blocked,' she continued in the cryptic code of the caller ID box.

The whiskered one sighed. 'You know, it could be my mother. She blocks her outbound caller ID.'
'An even better reason not to answer,' his loving spouse replied over the seventh, eighth and ninth rings.

Caller ID has been a boon to many, letting them avoid calls they would rather not field. Others still find it disturbing when someone answers saying, 'Hi, Susie,' before they even get a chance to announce themselves. And telemarketers and mothers-in-law ... well, they've been forced to new tactics such as message spam and increasingly bizarre calling algorithms. Or they just let the phone ring until someone answers out of frustration.

'Yallo,' the Rat growled as he finally grabbed the phone with his still-throbbing paw. 'Oh, hi, Mom. No, we weren't trying to screen you out.'

Somehow, the Rat suspects that the latest mutation of the caller ID concept will encounter similar problems in the proposals for e-mail caller ID. Sure, it might reduce spam, but it will just force spammers to get smarter. They might start sending their unsolicited e-mails from legitimate addresses.

'Yes, Mom,' the Rat sighed, 'it would be better if you didn't block your outbound caller ID. Then we might not mistake you for someone selling replacement windows. No, I don't think the black helicopters can track you down any easier that way.'

Rather than rely on some outside force'be it Microsoft Corp.'s Caller ID for E-Mail specification or the Sender Policy Framework that America Online Inc. and others have been trying to build'the Rat has been fine-tuning his own e-mailer ID concept.

All it takes is a short mail server script that works like this:
  • The script reads the sender's address.
  • The script reads the IP address of the mail gateway that sent the message.

  • The script does a reverse-Domain Name System lookup of the IP address. If the sender's address doesn't match that of the mail server, the script checks the mail server records for the domain that allegedly sent the message.

  • If one of the MX mail gateway records in the alleged source domain doesn't match the sender's server address, the mail goes to the bit bucket.

Of course, there have been a few hiccups along the way to e-mail nirvana.

'No, Mom, I didn't see your e-mail with the photos of the UFO you saw. It would help if you didn't try making up your own mail address anymore.'

The Packet Rat once managed networks but now spends his time ferreting out bad packets in cyberspace. You can e-mail him at [email protected].


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