How to properly set up DNS SPF records for a .local server?

Question

We send out mail via Microsoft Exchange 2010 running on a Windows Server set up as server.organization.local.

When error messages are generated it shows:

Generating server: server.organization.local

I am confused as to what our SPF records should look like based on this. Should it simply contain the external IP address that this server uses to send out mail, or both this .local address and external IP address?

Currently it is set as:

@ 10800 IN SPF "v=spf1 mx a:server.organization.local ip4:10.10.10.10 -all"

The mx is included to be safe but I'm not sure if it needs to be? The MX records on the domain name is set to a third-party filtering service, no mail is sent via it.

Answer 1

You need to specify the public IPs if you want to send emails to the internet.

If you are sending emails to another mail server on the LAN then you might have to add the private IPs as well.

I suggest to use a testing utility to check your SPF records.