Allowed Sender IP (DNS-Setting)

Help leak some information… how does more then one ip-addresses inserted here?

Separated by Comma, Whitespace, New-Line or something else?

BTW: If I change the IPv4 or IPv6 for the Allowed Senders it wont be saved.
If I come back to this dialog after save, the old IP is in the textareas.

It only work if I do manually edit the DNS-Record and add the TXT-Record for “spf1”

— own Answer
Got it! There is a Radio-Button to enable or disable SPF Record.
For better UX, I think if “disabled” is select, the rest of the form (anything that depend on SPF) should be hidden or grayed-out to not confuse the user.