OutSide Email Send issue

[It-infraadvantmed]

Hi Team, 

While sending email to Outside domain users we received NDR for those users with different details. so can you please le me know if we want to verify attached users are legitimate or not?

Please find attached users email id details for your reference. 

If you have any query or concern. please schedule call for the same.

[Dustin Anderson]

Your attachment is only really the subject and destination, so we can't really help you with that.

What errors are you getting back in the NDRs? Most usual would be DMARC or SPF. Of if your server is blacklisted. there should be a standard 5.x.x code in the NDR to show what the issue is.