Contact the recipient or the recipient's email admin and ask them to add the sender's email address or domain to the recipient's ...

  • Contact the recipient or the recipient's email admin and ask them to add the sender's email address or domain to the recipient's allowed senders list.
  • For more information and options to fix this issue search the McAfee Support Service Portal for 554 Denied.

Only the recipient or the recipient's email admin can fix this problem permanently. Unfortunately, Office 365 support can't fix these kinds of errors.