Delivery has failed

Glenn Maxwell 9,771 Reputation points

Hi All

I am using exchange 2016 hybrid environment. One of my user is sending email to external domain user and he is getting the below NDR. As per external domain user Message is being rejected by SPF policy. How can i check at my end if it is related to SPF.

Delivery has failed to these recipients or groups:
A communication failure occurred during the delivery of this message. Please try to resend the
message later. If the problem continues, contact your email admin.

Diagnostic information for administrators:
Generating server:
Remote Server returned '554 5.5.0 < #5.5.0>'

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
4,060 questions
Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
7,227 questions
Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
1,800 questions
{count} votes

Accepted answer
  1. Joyce Shen - MSFT 16,631 Reputation points

    Hi @Glenn Maxwell ,

    The sender may receive the following non-delivery report (NDR) that contains the 5.5.0 error code. This code indicates a generic SMTP failure.

    Typically, this problem occurs if the destination SMTP server performs a reverse lookup and if one of the following conditions is true:

    The IP address does not match the domain name that is used in the return address of the e-mail message.
    A pointer (PTR) record does not exist or is not valid for the source SMTP server's IP address.

    You may also take a look at the discussion here: smtp error 5.5.0 544
    That is an error being generated by your ISP. It isn't an Exchange error. You will need to contact them to establish whether they can support additional domains through their smart host.

    If an Answer is helpful, please click "Accept Answer" and upvote it.

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

    0 comments No comments

1 additional answer

Sort by: Most helpful
  1. Andy David - MVP 138.6K Reputation points MVP

    What indicator do you have its a SPF issue?

    That NDR can also mean the recipient rejected it as SPAM.

    You can check your SPF record to ensure its valid:

    0 comments No comments