
The TXT record value for SPF looks like this: v=spf1 mx include:Įdit the existing SPF record and add the Public IP address. Sign in to the domain’s registrar and open the domain DNS settings. The most secure way is to only add the Exchange Online IP addresses in the destination address and not ALL (everyone). To relay through Office 365 SMTP, you need to open port 25 from the organization firewall to external.


When you set up Office 365 SMTP relay, you will need to: Let’s look at how to configure a connector in Exchange Online for on-premises devices and applications for SMTP relay. Most IT environments have some applications or devices that need to send emails, such as:

