* This prevents dial-up clients from
sending mail directly to the world. Instead, they will be required to send all
email by way of your mail hub machines??”which PC mail-reading software can
easily be configured to do.
* There are many legal issues surrounding ad hoc filtering of customer access. You are strongly advised to consult
with an attorney before applying such filters.
This is the Title of the Book, eMatter Edition
Copyright ?© 2007 O??™Reilly & Associates, Inc. All rights reserved.
298 | Chapter 7: How to Handle Spam
??? On your mail hub machines, you will need to use any of the appropriate methods
discussed in the relaying section (?§7.4 on page 267) to enable the hub to
relay messages outward for your dial-up clients. By requiring that all outbound
email from dial-up clients be relayed through your mail hub, you enable your
hub to impose limits on sending rates, to limit the number of recipients per envelope,
and to log all email transactions. In brief, this puts you in position to detect
spam attempts by your customers.
??? A common technique used by spammers is to lie about the true host that was
used to send the offensive email by manufacturing headers that mislead the end
recipient. Suchh eaders can range from falsely made-up Message-Id: headers, to
misleading Received: headers. As an ISP, it is your responsibility to ensure that
all mail passing through your hubs is truthfully labeled.
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