Dialup Zones

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Here is a list of DNS zones that identify Internet hosts using dialup connections or other short-term dynamically assigned IP addresses. Many mail system administrators choose to refuse direct SMTP connections from these sources for several reasons: Thus, refusing direct SMTP connections from dialup computers forces them to use their ISP's mail relay. This makes part of the spam problem much easier for everyone (except the spammers, of course!) to deal with.

To use with Sendmail, simply include the current list of dialup zones in the access file with REJECT as the action.


This document was last updated by Jeff Makey <jeff@sdsc.edu> on 14 August 2012.