On Thu, Apr 10, 2003 at 11:38:30AM -0400, Liudvikas Bukys wrote
b. Initial email contact is not really known to be consented to, but
recipients can help senders through their filters by supplying
a proto-token as a free pass through incoming filters.
Can't the mailing list mention on its website what (sub)domain or
machine their mail is coming from ? rDNS can be forged, as can
envelope-sender. However, if you say that email will be coming from
machine bad.example.com, then it's a simple matter of comparing output
from a domain lookup of bad.example.com against the IP address of the
MTA sending you the email. Note the following...
[m1800//home/waltdnes]host cnn.com
cnn.com has address 64.236.16.84
cnn.com has address 64.236.16.116
cnn.com has address 64.236.24.4
cnn.com has address 64.236.24.12
cnn.com has address 64.236.24.20
cnn.com has address 64.236.24.28
cnn.com has address 64.236.16.20
cnn.com has address 64.236.16.52
..yes, one name can return multiple addresses. This allows backup MTAs
and load-balancing. Going via DNS also means that...
1) You can change IP addresses, and DNS will still get you there.
2) During a switchover, you can list both old and new addresses.
--
Walter Dnes <waltdnes(_at_)waltdnes(_dot_)org>
An infinite number of monkeys pounding away on keyboards will
eventually produce a report showing that Windows is more secure,
and has a lower TCO, than linux.
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