I’m still using Interworx v. 6.x. If I look at a Siteworx account, and go Domains -> DNS Records, then click the Edit link for an SPF record, I now see that I can select either version 2 or version 3 of SPF. It looks like all selecting SPFv3 does is change the “v” tag to “v=spf3” and doesn’t make any changes to other tags or offer new options in the UI.
I haven’t been able to find anything relevant about SPF v. 3 by Googling it. What, if any, are the reasons to select SPFv3 vs SPFv1?
The one believe I have is spfv3 is not fully used or setup in most email servers, so it is not checked whereas spfv1 is widely used (apologies if I am wrong)
To answer your question, please see here
Are SPF and Sender ID the same?
SPF and Sender ID are not the same. Both validate e-mail sender addresses, and both use similar methods to do so. Both publish policy records in DNS. Both use the same syntax for their policy records. So you have some excuse to be confused. They differ in what they validate and what “layer” of the e-mail system they are concerned with.
That is some confusing stuff, but if I am reading it correctly, both SPF2 and SPF3 are for Sender ID and not SPF, and are thus “obsolete and independent protocol[s]” and not the latest version of SPF, so that I should be using SPFv1 on all my Siteworx accounts for routine SPF.