550 Rejected by header based Anti-Spoofing policy

A document by KCS Integration on behalf of 76e6cae21521beeb07a7db4b1aabb71a50457597 on Mar 21, 2018Last modified by Roxann McGlumphy on Mar 22, 2018
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Issue Description
Issue in delivering Marketo Email (especially for mimecast users). Email get bounced with Error: 550 Rejected by header based Anti-Spoofing policy


Issue Resolution
This error can happen if:


You have not properly white listed the Marketo IPs

You have an ssue with DKIM/SPF set up and configuration


Please whitelist the set of Marketo IPs found in the doc below and make sure SPF and DKIM are set up correctly for your email domain