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Spam is causing real mail to be delayed

Dear experts,

I have an SBS2003 box. Standard enough setup - nothing fancy, 20 users. Mail is delivered directly to the SBS box. Recently the amount of spam which we receive is unbelievably high. Daily we receive 100,000 +  emails of which probably around 120 are legitimate. 99.9% of the spam are for nonexistinguser@domain.com

I have GFI Mailessentials installed to manage the spam and it is working well - it blocks the spam and delivers the real mail. But the problem is that the real mail is taking so long to arrive. Having done a few tests, the fastest took 25 minutes to deliver. A lot of the time, senders get "message delayed" messages sent back.

The way I see it, if the mail is delivered to the ip address (according to the mx record) which is the router, then it has to deal with it. The traffic is already present on my system.

Is there any way I can get the spam dropped before my system has to process it?

I have been considering a few options:
1. Have the ISP host the email to let their spam filters do the most of the work, then collect mail using POP3 connector
2. Change our mail domain - a bit drastic I know.

I'd rather not do either option. All help appreciated.

Thanks in advance.
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Co-Owner
Top Expert 2011
Commented:
I use Vamsoft ORF (www.vamsoft.com) and it has two delivery points for spam checks:
Before Arrival and
On Arrival
Most spam gets rejected before arrival, so before most of the message has actually been transmitted and you can choose to drop the connection if the message is deemed spam, so that you don't have to receive the message first and then decide if it is spam or not.
I have not usd GFI mail essentials so don't know if it works in a similar way, but if it does, then offloading to an Anti-Spam appliance such as a Barracuda device would seem a good route to go.
My own server receives about 15,000 messages a day.
Vamsoft has handled 8.8 Million messages over the course of 11 days quite successfuly for Simon Butler aka Mestha (one of EE's top Experts):
http://blog.sembee.co.uk/post/Truly-Spectacular-Results-from-Vamsoft-ORF.aspx
Alan HardistyCo-Owner
Top Expert 2011

Commented:
On the plus side - it only costs $239 per server - one off cost with an optional $99 annual fee to keep the software up-to-date.
Hi. A couple options.

Take some load off your SBS and setup up a dedicated Linux mail server on your front-end. Use AV/Spam/greylisting/blacklisting and setup user reconciliation so it will drop unknown users.

Move to a hosted solution such as Postini or MXLogic. This is always nice since I'm sure you won;t have to worry about their servers handling it.
I second the suggestion on Vamsoft ORF as a past user. Best on a front-end though if you can afford.

Author

Commented:
I had a look at the Vamsoft product and will be using it for sure.

I am accepting this as a solution having read Simon's review and going on your recommendation.

Thanks for your help.
Alan HardistyCo-Owner
Top Expert 2011

Commented:
If you get stuck with it or need help configuring it, please just post another comment.
It is relatively straight forward to configure (add all the detail to the logs) and the logs are briliant.
Thanks for the points.
Alan