To help ensure that notifications from our EVE hosted forum get to the email boxes we have generated an SPF record in our domain's DNS root server. Currently it looks like email notifications are sent from 18.104.22.168 for our postings. We set up an SPF record for that IP address and it is logged as "pass" in the test Google email account we use to monitor postings. Is this the only SMTP server that is used? If not, what is the range of SMTP servers we should include in our SFP record for our domain?