554 Denied - Error Message

Hello,

Our company has recently been receiving the following (and attached) error message more times than we are used to.  This has not been an issue until the last couple of days.  The error message says that it's on the recipients end, but we've been emailing people we've been in contact with via email previously.  This leads us to believe it is not on their end and on our end.  Is there some maintenance work or something else being done to affect how other domains are receiving out emails?  I'd say this happens to maybe 10% of our emails going out.

Your message couldn't be delivered because the recipient's email system reported the following error: '554 Denied [CS] [3f0f8965.0.9974440.00-2121.19901702.s12p02m042.mxlogic.net] (Mode: normal)'. It's possible it's a temporary issue with their email system. Try to resend the message. If the problem continues, contact the recipient by some other means (by phone for example) and ask them to tell their email admin about the problem. Be sure to give them the error above, as it will better help them diagnose the problem.

For Email Administrators
This error is being returned by the recipient's email system but it doesn't include a valid, specific, enhanced SMTP status code, making it difficult to assess exactly what the problem is. Please carefully examine the error reported by the recipient's email system to help diagnose and troubleshoot the problem. Only the recipient's email admin will be able to fix this. 

s12p02m042.mxlogic.net gave this error:
Denied [CS] [3f0f8965.0.9974440.00-2121.19901702.s12p02m042.mxlogic.net] (Mode: normal) 

Hi James,

To narrow down the issue, I’d like to collect some information:

1. Does the issue occur when you send emails to all recipients in that organization?
2. Do you have any issues when sending emails to others?
3. Can you provide the full non-delivery (NDR) report? To protect your privacy, I have sent you a private message to collect them. Please click on the link below to access to your Private Message：

https://community.office365.com/user/conversations

Best Regards,
Erick

Hi James,

Can you provide the information I asked for at your convenience?

Best Regards,
Erick

1. Yes.  (ex. (removed by moderator to protect your privacy) is a domain that seems to be kicking back our emails.  They are a frequent target of our emails.

2. Not all domains are kicking back out emails.

3. I responded to your message with the domain.

The previous representative stated that we need to have the companies that are kicking back out emails change their settings.  How would this make sense if we've frequently sent/received emails from many other clients with the same domain up to now?

Hi James,

Thanks for your information.

I have checked all NDR and noticed that emails have been delivered from Office 365 servers. Based on the error message, the issue is related to recipient’s side. I understand that you can email them before. Since the configuration of email system may be changed at any time by recipient’s admin or mail providers, given the situation, we suggest you contact the recipient’s admin or their mail providers. Based on my experience, you can let their admin check related rules or block list. If they have any 3rd party mail filters, they can also check it and add your domain to the white list to check whether there is any improvement.

If you need any other information from Office 365, please feel free to let us know. Your understating is highly appreciated.

Best Regards,
Erick