It is important for deliverability reasons to use HTTP port 80 for
open and click tracking. If you have IIS installed, by default it will
take ownership of port 80 on all IP Addresses. When this happens,
setting the MTA to use port 80 will result in the error below when
starting the server.
System.Net.Sockets.SocketException (0x80004005): Only one usage of
each socket address (protocol/network address/port) is normally
permitted at System.Net.Sockets.Socket.DoBind
To fix this on Windows Server 2008 and later you can use the netsh
command line tool to release port 80 for IP's not being used by an IIS
web site.
To display all IP addresses in the IIS IP listen list
netsh http show iplisten
To add an ip to IIS
netsh http add iplisten ipaddress=1.2.3.4
To remove an IP from IIS
netsh http delete iplisten ipaddress=1.2.3.4
Be sure to test your IIS websites after using these commands to ensure
that there were no unintended consequences.
You can find more information at
http://technet.microsoft.com/en-us/library/cc725882.aspx#BKMK_11
[http://technet.microsoft.com/en-us/library/cc725882.aspx#BKMK_11].