https://community.mimecast.com/docs/DOC-2545#jive_content_id_Inbound_DNS_Authentication_Policy_Configuration You can also tighten down SPF to only allow specific email address to send from third party services instead of whole domain : https://www.jamieweb.net/blog/using-spf-macros-to-solve-the-operational-challenges-of-spf/
Tag: mimecast
Mimecast – Connection Attempt – Attempt Greylisted
Find the email in Administration – Gateway – TrackingSee : Connection AttemptGo to Administration – Monitoring – ConnectionsSee : Attempt GreylistedGo to : Gateway – Policies – GreylistedAdd new Policy […]