Yes, it is possible to edit the SPF record for your domain in Office 365, including adding additional IP addresses or mechanisms such as the "p4" mechanism you mentioned. However, modifying DNS records, including SPF records, typically requires administrative access to your domain's DNS settings.
Learn how to update a Domain Name Service (DNS) record to use Sender Policy Framework (SPF) with your custom domain in Office 365.
Set up SPF identify valid email sources for your Microsoft 365 domain ...
Admins can learn how email authentication (SPF, DKIM, DMARC) works and how Microsoft 365 uses traditional email authentication and composite email authentication to allow and block spoofed messages.
How can make a change to the SPF record for my DNS which is hosted by ...
Sender Policy Framework, better known as SPF, helps prevent email spam. SPF is designed to help prevent spoofing. Activate SPF on a domain by adding a TXT record to the domain's DNS. To set up an SPF TXT record for use with Microsoft 365 email services, see Add an MX record and DNS records for email (Outlook, Exchange Online) in this article.
Email authentication is a critical component of securing communication in your organization. When an email is received in Microsoft 365, the service adds an Authentication-Results header. This header shows the results of various email authentication checks, including SPF, DKIM, DMARC, and composite authentication (compauth). This guide explains common scenarios you might encounter with these ...
SPF records are TXT records that help to prevent other people from using your domain to send spam or other malicious email. Sender policy framework (SPF) records work by identifying the servers that are authorized to send email from your domain. You can only have one SPF record (that is, a TXT record that defines SPF) for your domain.