wcSMTP and iprelay.dat
wcSMTP will now recognize a file called iprelay.dat
in the server config subdirectory. This file specifies which hosts will be allowed to "relay" through wcSMTP. Relaying is defined as the ability to send a message to a user who is NOT in one of the local domains. This file should contain a list of IP addresses and masks in the following format, one per line:
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209.31.204.0 255.255.255.0
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The first IP address is the address of the host or network to allow, and the second field is the
subnet mask to apply. This example allows all addresses in Mustang Software's class C network to relay. If the mask is omitted, only the specified host will be allowed to relay. This file must only
contain IP addresses; no DNS lookups will be performed. This file is read at wcSMTP startup -
changes made to this file while wcSMTP is running will not take effect until wcSMTP is restarted.
If this file is not present, wcSMTP reverts back to its previous behaviour of allowing a send to a
non-local address if the From field is a local mail domain. This leaves open the possibility of a spammer using you as a relay AND spoofing mail from a user in your domain.
Note that relaying is always allowed from local connections (ie. from a program running on the
same computer as wcSMTP). This is so that programs like wcListServer can still do their job. The /allowrelay
command line switch turns off all of the above and always allows anybody to relay (this is NOT recommended for a mail server on the Internet, because sooner or later you WILL be
used as a spam relay target!).
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