XFOR: Setting Accept/Reject by Host in IMC Connection Settings (155920)

SUMMARY

The Microsoft Exchange Server Administrator's Guide, pages 332-338, explains how to set up the Connections Property page for the Internet Mail Connector (IMC). However, the documentation on Accepting or Rejecting by Host setting does not state the effect of setting this feature, that is, whether a Non-Delivery Report is sent or connections are simply refused.

If you set the Reject by Host setting, all hosts that fit that masked IP range will get the following error when attempting a connection:

521 <Domain Name of Server you are connecting to> access denied

If you set the Accept by Host setting for a Masked IP range that falls under an entry for a Reject by Host, the Accept by Host will override and allow a connection.

MORE INFORMATION

On the Internet Mail Connector property page, on the Connections tab, under Accept or Reject by Host, you see the following items:

   First Entry:
   IP Address = 157.57.10.0
   Mask = 255.255.0.0
   Action = Reject connection from this Host

This first entry will reject all connections from class B domain 157.57.

   Second Entry:
   IP Address = 157.57.10.0
   Mask = 255.255.255.0
   Action = Accept connection from this Host

This second entry will accept a connection from class C domain 157.57.10, regardless of the restriction set in the first entry. Host 157.57.10.25 will be granted access. Host 157.57.15.2 will be denied access.