Exchange as a relay /Spam server

[gfunk123]

We are running exchange 5.5 sp4 with an IMC. All of our mail is treated as inbound because the IMC option "Do not reroute incoming SMTP mail" is selected. We have employed the services of a 3rd party software provider who have set up an internal SMTP server to aid the functionality of their software, e.g. 'server.NTdomain.com'. We have had to set up an exchange account with an SMTP address that we will advertise to the public, which when received by exchange will forward ,via a custom recipient to the SMTP server sitting on the 3rd party Server (which incidentally is on the same LAN. To do this however, it has been requested of me to switch on the setting 'Reroute incoming SMTP mail' and add an entry in the routing box to accept mail with the domain name eg.'server.NTdomain.com' specified by the custom recipient)

My concern lies with the fact that every administrator and IT bod I have spoken to seems to think that by selecting this option we will be at risk of opening ourselves up as a relay/spamming server and could be black listed as a result. Is this true?? I am slightly worried that there are options to add servers to the routing table but no option to 'reject everything from everywhere else'

Am i getting too paranoid or should I presume that microsoft would have had the forsight to fix this (supposed) problem in SP4 (which I have applied). Or are there actually no issues with this feature?.

Any help or advice on this sensitive issue would be greatly appreciated

Ta

 

[JWilliams]

Here is an article that will explain how to setup your Routing tab and how to test and verify that you are not an open relay. It helped me feel safe about relaying, hope it helps you too.
Jessica

http://www.exchangeadmin.com/Articles/Index.cfm?ArticleID=7696