BDP File

What are BDP files and how to open them

Are you having problems opening a BDP file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BDP files.

What is a BDP file?

A .BDP file is a Microsoft Exchange Diagnostic Message file.

Microsoft Exchange Diagnostic Message File (.BDP) is a kind of "diagnostic message" file used by Microsoft Exchange Server when an email could not be delivered to its intended recipient. It stores metadata about the failure and points administrators to a local .EML file that typically contains a non-delivery report (NDR), which explains why the message delivery failed.

These .BDP files are placed in Exchange's Badmail folder, alongside .BAD files (the undeliverable message content in SMTP/native format) and .BDR files (which contain error code information). When Exchange generates a BDP, the corresponding .EML file may include the full NDR content. The Badmail folder exists so administrators can review, retry, or remove undelivered messages and their diagnostic information. The Badmail feature must be enabled in the server configuration - on systems like Exchange 2003 SP1 it is disabled by default.

These files are plain text references rather than binary objects: a BDP file contains text pointing to a local path (for example, the .EML file). Every .bad message in the Badmail folder has matching .bdp and .bdr files. The contents of BDP are small and are not the NDR itself but pointers/diagnostic references.

How to open BDP files

We have identified one BDP opener that is compatible with this specific type of BDP file.

Programs that open Microsoft Exchange Diagnostic Message files

Last updated: August 5, 2026

Various apps that use files with this extension

These apps are known to open certain types of BDP files. Remember, different programs may use BDP files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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