A client of mine has asked me to "rightsize" their IT Infrastructure. What SPAM filtering solution do you use and why?

“...., I work with various solutions in the market. Let me try to categorize the e-mail anti-spam solutions by architecture: 1- Gateway level solutions: Usually an inline server catches the spam traffic at your infrastructure before it hits your e-mail servers (in your case MS Exchange). The advantage is that your server resources are not hit by spam processing. 2-Server level solutions: You can deploy anti-spam solution on your mail gateway. The spam will be filtered before it hits the user mailboxes. 3-Hosted anti-spam services: This is the world of software as a service :). You may simply redirect your mail traffic to a service provider (e.g. Postini, MessageLabs, Frontbridge). This solution filters spam even before it hits your internet pipes. SMTP traffic (so MX records) is redirected to a service provider so all the mail is filtered before it is redirected to your site. These services are managed solutions you do not need software or a gateway, everything can be handled on the provider side. 4- Client level solutions - Antispam is filtered at your e-mail client application (e.g. Outlook, Eudora, Thunderbird).. This solution is cost effective for individuals and very small shops, but it is not an infrastructure solution. That being said, there are several quality factors that you may check to find the right sized solution: 1- Is your operation subject to any compliance requirements? 2- What is the OPEX for the planned anti-spam solution? 3- What are the end-user interface requirements (categorization, white/black lists), how flexible is the management interface? 4- Do you require anti-virus integration? Do you require encryption support? 5- What kind of notification systems do you need for spams? Reporting requirements? 6- How many messages do you receive per day? Do you have latency requirements? Do you have/require SLAs? 7- Do you have high availability requirements? And the list goes on. We work with many of the gateway solutions, and we offer and use a hosted solution, which works for our operation. If you have any questions I would send the names and the resources for your research,let me know. regards, - yinal”