Requirements for a DMARC policy to pass for sends through the Marketing Cloud

For DMARC to pass, you need one of following 2 identifiers to pass: 

1) For SPF Alignment these two need to match. 

• The "From" address domain 
• The Return-Path (Mail From) domain 

The Return-Path domain is also sometimes called the Bounce Host or Bounce Domain. 

2) For DKIM Alignment these two need to match. 

• The "From" address domain 
• The DKIM signature domain (d=domain.com) 

Some email providers apply a stricter standard -- where both SPF and DKIM must align. When the authenticated sending domain differs from the SAP domain, SPF will be out of alignment because the bounce domain will not match the sending domain. This can cause message rejections at stricter email domains. 

Multi-Bounce Domain support can be enabled to have bounce domains be set on a per-message basis to reflect each From address's domain. The bounce domain is generated by prefixing the authenticated domain with bounce. Please open a support case to enable Multi-Bounce domain support.