The reason for the error message „spf check failed“ is an incorrectly configured sender policy framework (spf). This policy is meant to prevent the falsification of the sender address of an e-mail. The owner of the domain needs to specify which computers are allowed to send e-mails for this domain in the domain name system.
For eTermin to be able to send e-mails using your domain, please specify the address of the eTermin mail server: m.etermin.net and m2.etermin.net. The updated spf record could look like this: "v=spf1 a mx include:m.etermin.net include:m2.etermin.net -all".
Notice: If you created a security rule that bans mail traffic from your domain through an external server please note that additionally to the spf record you need to add our IP-address, which is referenced to in the spf record, to the mail traffic rules of your Exchange-admin-centre.