Outbound message failure: Mimecast Error: 550 Administrative prohibition - envelope blocked

Last Modified

Thu Dec 08 13:20 GMT 2022

Description

  • Outbound emails are being rejected by the recipient with a error 5.0.0 smtp; 550 Administrative prohibition - envelope blocked
  • Rejection message shows "Remote Server returned '<us-smtp-inbound-1.mimecast.com #5.0.0 smtp; 550 Administrative prohibition - envelope blocked - https://community.mimecast.com/docs/DOC-1369#550>' "

Environment

  • Mail Assure

Solution

  • There are two reasons for this issue:
    1. The sender's email address or domain has triggered a Blocked Senders Policy on the Recipient's main server
      1. Contact the recipient via another method and ensure that the sending domain or address does not feature on a sender Block list
        1. If present, have the recipient remove the sending domain or address from the Block list
    2. There is a SPF hard rejection on the sending servers SPF record
      1. Confirm the SPF record is correct to allow mail to be sent through Mail Assure
      2. Full details can be found here: Set up SPF