We are continuing the research and evaluation process of migrating from Exchange 2000 to Exchange 2007. One of the roles that I am in limbo with but think I may now know where I am going with is our perimeter SMTP role. The options in the thread subject are what I am weighing. I will begin by saying what I think will be our best option and why, and then what I will want to know is whether I am missing something with the other. I think IIS6 SMTP with our filtering solutions installed would be the best solution.First of all, we already pay for and use GFI MailEssentials 12 for our spam filtering. I know this solution very well. It has a high accuracy rate and catches nearly all the spam we get. I really have no desire to learn a new solution (what Edge provides) and risk the probability of letting more spam though because of not having the spam filters in the Edge server not tweaked properly. I've heard many reports of people not being happy at all with the effectiveness of the filtering in the Edge Transport server, and I'm sure this is mostly just because of not having the filters tweaked properly. I know I would easily become one of these people and not quite get the filters right. Long story short is I'm happy using GFI and don't want to use another solution. The same really applies to our anti-virus solution as well.So outside of this, I don't see what else that the Edge Transport server would offer over an IIS6 SMTP server with our anti-spam and anti-virus solutions installedhttp://technet.microsoft.com/en-us/library/cfff9f59-afac-447c-8297-afcebe49a52d.aspxAddress re-writing and transport rules are the only other things I see on the above page that an Edge Transport server offers. GFI MailEssentials again offers some transport related functionality that we might need, but otherwise we don't need these things. We're a small organization of about ~110 email boxes. We don't have complex needs with our email, really... just one internal Exchange 2007 server (Client Access, Hub Transport and Mailbox server roles) and we'll have one perimeter server.So, with all of this said, am I missing something that an Edge Transport server offers that I couldn't cover with an IIS6 SMTP server with our filtering solutions installed? Thanks for any advice about what I might be missing in my decision making and rationale.