It seems (?) like most services add IP addresses to the SPF record, but I noticed mailinabox does not. Any reason?
I’m not aware of any particular reason for this setting to be configured as is, other than a restoration from backup will be somewhat more portable because
mx can be resolved to whatever your MX record is, but the IP address is fixed so has to be manually changed, which means someone has to write a script for if this changes, or it has to be manually changed.
You can change it. I never use the default because if you have more than one server sending mail on behalf of a domain, the default SPF cannot work.
Ahh, that makes sense. MX would reflect back to the correct IP at all times, if you’re doing DNS from the same box. Single source of truth. Always thought it was odd most seem to set “ip4:” but I suppose they can’t make the same assumptions about DNS that MIAB can.
I definitely did not think of that when I programmed it, but it’s a good point.
Simply because there is no reason as the MX record will always point to the MiaB server, so that is covered.
Most of the time when you see an
ip4:111.222.333.444 in the SPF record it is because that domain is sending emails directly from their web server.