Anyone implemented SPF on OS X Server?

So, I do not have an exact answer to your question, but it may help. I've been running ASSP as a front end proxy to my OS X mail server for going on 10 years now. It does do SPF and a lot of others things too.

Yes, that's the one!

There are two aspects potentially.

You need the SPF record added to your DNS server, this DNS server might be an external DNS server but you may also have an internal DNS server as well. (This is called a split-horizon DNS configuration.) If so you need to add the SPF record to both DNS servers.

To add special records like an SPF record the Server.app program is not really up to the job, you therefore need to manually edit the appropriate file in /Library/Server/named/ while your DNS server is temporarily turned off.

The second aspect is your mail server software, Kerio Connect has built-in support for SPF and it is merely a matter of turning this function on, but if your using the Apple mail server which is part of Server.app then you need to enable support in whatever anti-spam system you are using, as per other answers here one option is to do this using ASSP another is to do this using SpamAssassin which is built-in to Server.app although only configurable via the command line.

Once you have SPF working you can move on to setting up DomainKeys.

LOL. 😀