Messaging Gateway

Hello,

We have an issue with incoming e-mail at a customer site. They are currently overwhelmed with incoming message, and SMSSMTP can't seem to handle the load, or SMSSMTP can't deliver the mail fast enough to the internal mail server. The customer is pretty large, so he's getting lots of incoming mail, but we see that SMSSMTP is only opening 8 connections to the internal server.

It's not the firewall that is limiting the connections, nor the mail server (if SMSSMTP had it's 8 connections open - as found using a netstat -an command), i can do a telnet on port 25 from the SMSSMTP server to the internal mail server without any delay).

The parameters in SMSSMTP which define the maximum number of connection in the scanner are set to 100 (default value was 50). But, in my case, it's only using 8 connections simultaneously (and sometimes less than 8).

In fact, to deal with this on short term, we've installed a second scanner and changed the mailflow so that it's handled by this scanner, and it's also opening maximum 8 connections at a time.

Strange thing is that the Inbound queue keeps building up, the Delivery queue remains almost empty. It looks like the legitimate messages aren't passed to the internal mail server fast enough.

Will the performance of an Symantec Brightmail Gateway appliance be any better? Is it worth the try?

Regards,

Olivier

We are using SMSSMTP 5.0.1 patch 2000 on a Windows Server 2003 SP1 Standard platform. The hardware is an HP ProLiant BL460c Blade server with dual core CPU and 2 GB RAM.

They get about 8,000 messages per hour, half of those is spam (directly deleted, not quarantined).

I'm learing the new forum features, I didn't see the Edit button...

So I'm not entirely sure why we would only make 8 connections to your mail server, but to be honest, it may be all we need with the way that we process mail. Most mail servers can do what is often referred to as "pipelining" that basically boils down to sending multiple mail messages over a single connection. Since we are only connecting to your mail server we wouldn't necessarily need a huge amount of connections.

You are most likely just running into a limit in our ability to process the amount of mail you are receiving concurrent with your policies. I wouldn't say that generally 8,000 an hour is a huge amount, but it really depends on what all the box is trying to do.

Maybe we could get a little clarification on whether you are using compliance filtering and possible DNS block lists? Deletion of spam is a plus, so good job on that one.

Performance WILL be better with the Symantec Brightmail Gateway. I don't think we are really questioning whether or not it will out perform SMTP5 at this point. So I would at least suggest looking in to this.

Let me know what else I can help with.

Thanks!

Tom

We are indeed using two DNS based third party blocked sender lists. I have now disabled these, and the inbound queue is immediately empty. We don't have many content filtering rules.

The problem is solved, apparently the third party DNS lists didn't respond fast enough.

Thanks for the assistance, Tom. The problem is solved.

Thanks for the update Olivier. Happy everything is working ok for you now!

FYI, we were still using list.dsbl.org. Apparently, that list is suspened in May 2008, but it still responded until the beginning of this week. Since the 9th of March 2009 the server doesn't respond any longer. This is what caused the delay...

Olivier