Here's my experiences with using Smartermail Gateways for both Inbound and Outbound traffic:

 

 

Despite the little (and big) problems running Smartermail this way, we can't imagine going back to one Mail server does it all ever again. Having separate Gateways to handle processing email is too much of a necessity if you have medium to high email traffic.

Great response, Scarab!

Maybe it's our email gateway that is not set-up correctly  but the one issue, reported by Scarab:
 

There is one more thing with outgoing gateways and it is related to IDS block possibilities. Gread IDS solution Bounces Indicate Spammer will not work on them.

 

"Bounces Indicate Spammer - Enabling this rule in SmarterMail will block or quarantine an account from sending out mail, as well as alert an administrator, after receiving a certain number of bounce messages in the specified time frame."

 

so if message is bounced on outgoing gateway then there is no way to block user account since it is located in primary SM. I would love to have this in scenario where outgoing gateways are used.

A follow up to many of the problems we have been experiencing with Smartermail Gateways.

We have been using Smartermail Gateways as both Incoming *AND* Outgoing Gateways to our Smartermail Enterprise server. The reason we had this configuration was to offload Spam & Antivirus checks on both Incoming and Outgoing email to another server(s). As we used Declude and HijackThis, which are both CPU and Memory intensive, at the time we felt this seemed like a smart move...and it worked relatively well with the exceptions I noted in my posts in this thread.

 

Recently, after upgrading to Smartermail v14, we had the need to stop using our Smartermail Gateways for Outgoing (having to do with one of our hosted domains being a split domain that has email hosted both at Google Apps and on our Smartermail Enterprise server), and use our Smartermail Gateways only for Incoming . In the two days since almost all of our problems that we had experienced when using Smartermail Gateways cleared up.

 

The moral of this cautionary tale is that Smartermail Gateways work great as *EITHER* an Outgoing Gateway or an Incoming Gateway, but things may begin to work not as intended when you try using Smartermail Gateways as both.

There is one thing I ran into with the Outgoing Gateway. Using webmail, the Outgoing gateway does not work for local deliveries. Deliveries within domains on the Smartermail webmail interface do not use the Outgoing Gateway. All deliveries are done internally. If you use a client, it works fine. So if you need to pass all traffic regardless of the address to an Outside SMTP server, you will have this restriction. I have been on Smartertools back for over a year about this and they won't change it. I have not renewed my license because of this and moved to another software. Shame since I liked Smartermail better in all other features.