Our business currently has our email hosted with our dns provider and locally we have a watchguard firebox with all of the software subscriptions. The firebox has a great spam filter and quarantine server, however the smpt filtering (quarantine feature) only works if you have a smtp server behind the firebox.
Is there anyway to have our dns provider change our mx record to point to us, have the firebox filter the email and then push the email back to the isp so that clients can download the email via pop3 with their outlook clients? Our dns provider is willing to change our mx record but we are stuck on how or even if it is possible to "scrub" the email and then send it back to the provider.
Our goal is to not have to get a mail server onsite as it would create another server that needs to be maintained. Although, if anyone has any other suggestions that would be great as well.