SPF Record allows other servers to send E-mails on behalf of the actual server that the domain is appointed to. There can only be one SPF Record for a domain, so the new SPF Record must be changed but NOT added. In order to change the SPF record, you must access your DNS console, which may differ depending on your domain registerer.
Please change the existing record from:
"v=spf1 include:spf.protection.outlook.com -all"
"v=spf1 include:spf.mta.hdems.com include:spf.protection.outlook.com ~all", you can also find this value in your Connection Settings File.