Anti-spam hosting can be done in a number of ways. One of the most common forms of hosting is through ISPs, who will often add it on as a free extra or at a small cost per mailbox for small businesses who have their e-mail hosted by the ISP.
IDC's Dahlgren says the ISP offering is the most common for the SMB space. "These offerings are very inexpensive and they are often quite relative to other offerings in terms of quality," she says. But senior security analyst with Symantec Andrew Gordon says some ISPs view bandwidth as money, and can be less likely to do a thorough sort through spam if it reduces their traffic. "It is best to go with a managed hosted solution by a specialised provider if you want more than your ISP can offer you," he says.
A common form of hosting is where the hosts intercepts the mail and scans it for spam before the mail reaches your gateway. In this case the host will completely run and deliver the e-mail scanning infrastructure, checking e-mails before sending them through to the client's e-mail server.
For example, MessageLabs technical director David Banes says the company will analyse traffic patterns, carry out content analysis, and use its database of known spam to score e-mails on their legitimacy before pushing the "clean" mail through to a client's server.
"This is different to a normal desktop product that will simply look at an e-mail that comes in, check out its characteristics and decide if it is a virus or spam, unless configured by the user themselves," Banes says.
Dahlgren says the option of having a host sit in the pipeline between the sender and the mail server is relatively cheap -- it could start with one start-up fee, generally around the AU$200 mark with each e-mail address charge of a monthly fee after that, up to about AU$5.50 per user. A good price for a small business, but enterprises may find the option a bit too costly, she says.
Another way of hosting spam involves complete mail server management -- where the customer's mail server is located and managed by the host at the host's site. In this scenario, management services extend beyond anti-spam to include antivirus scans and back ups, and hardware and software management.
This option is hardly ever used for anti-spam itself, according to Dahlgren. "You would generally have your e-mail server stored with the host from the beginning, and you would just ask your host to turn on your anti-spam. The cost of anti-spam would be included in the total cost of your server hosting," she says.
I think hosted anti-spam IS the answer. I use the Gmail solution: http://www.iopus.com/guides/gmail-spam-filter.htm