Microsoft 365 (Exchange) Setup Guide

Configure Office 365 / Microsoft Exchange Online for full authentication compliance.

1. SPF Configuration

Include the standard Microsoft protection mechanism in your SPF record.

2. DKIM Configuration (signing)

1. Log in to the Microsoft 365 Defender portal.
2. Go to Policies & rules > Threat policies > Email authentication settings > DKIM.
3. Select the domain you want to sign.
4. Toggle "Sign messages for this domain" to On.
5. If the toggle is greyed out, you must create the CNAME records first:
   • Selector 1: selector1._domainkey -> selector1-yourdomain-com._domainkey.yourdomain.onmicrosoft.com
   • Selector 2: selector2._domainkey -> selector2-yourdomain-com._domainkey.yourdomain.onmicrosoft.com