Exchange Server non-delivery reports (NDRs) indicate email delivery issues. Causes can include non-existent, inactive or expired accounts, unresolved recipients, misspelled email addresses, SMTP problems, spam, poor spam filter configuration, a full BADMAIL folder, missing reverse DNS entries, and firewall interoperability issues — just to name a few. Get tips on enabling and disabling NDRs, and learn how to decipher and troubleshoot NDR messages in this collection of expert advice.
Frequently Asked Questions: EXCHANGE SERVER NON-DELIVERY REPORTS