Spam is Killing Me - Can I use GMail as a spam filter?

Look into the Postini services from Google.

"Yes, Gmail can filter your spam if you route all your mail through it. But you will need to forward your mail a couple of times. If you prefer Gmail, then you can skip steps 2 and 3!

Set all your mailboxes to forward all mail to a single target Gmail address.

Don't read mail in those mailboxes anymore. The target Gmail address works as your spam filter for all your above mailboxes.

In that target Gmail account, set up a rule to forward everything to a new mailbox. This rule will forward everything except the caught spam, and that's exactly what you wanted.

This could be a new Gmail account or a new Exchange account; whatever you prefer. The address of this mailbox is irrelevant and should be kept secret.

Use the new account as your only account, and set it up so that the sender and reply addresses are whatever you want your ""official"" address to be (regardless of the actual address of this account).

Only tell people your ""official"" address, not the address of this account.

Now, any mail to any account will be filtered by Gmail and then sent to your new account."

"The question probably belongs on SuperUser, but...

How are you accessing you Exchange email? If you're using Outlook, you could use one of the spam filtering plug-ins for that. If you're using web access, you're stuck with whatever the hosting provider is doing (or not doing).

If you wanted all your mail to go through Gmail, you'd have to use that as your primary address, forward all the messages from there to your Exchange account, and have a Reply-To address set on your Exchange mailbox that's your Gmail address.

Edit: your comments make it sound like this hosted service is used for your company. If so, isn't there any pressure you can exert on the vendor to add spam-filtering?"

You can try ASSP http://assp.sourceforge.net , install on vps or dedicated server and point your MX to assp. Assp will forward your email to hosted MS Exchange.

You can check out SAFENTRIX. Has both Free (Standard) and paid edition and is as maintenance free as anything can be.