File Extension is group of letters that specify the data type in the file and helps windows to select the appropriate program to open the particular file .BAD Extension File stored in Microsoft Exchange Server BadMail folder and it contains all non-delivered emails.
Before discussing BAD File lets first discuss what file extension is? And why we use it. The file extension gives general description about what type of data the particular file contains and this information helps computer to call the appropriate program to access the file. Windows stores description of each file extension in windows registry.
User can request any type of data file to open, then computer need to recognize the particular file contains which type of data and which software will support it. In this situation the file extension helps the computer to recognize the data type of requested file and then calls appropriate software.
Exchange server is a mail server that enable a user to send or receive the mails. But many time it is unable to successfully deliver the email to the specified receiver then a non-delivery report (NDR) error message is generated by Exchange Server with the explanation of reasons and circumstances due to which E-Mail was not delivered and return by the server to the sender as an acknowledgement. The returned mail or .bad files are stored in Bad mail folder together with .BDR and .BDP Files.
Location of BadMail Folder
Location of BadMail Folder on the system which is running the Exchange Server.
C:\Program Files\Exchsrvr\Mailroot\vsi 1\BadMail
Location of BadMail Folder on the system which is not running the Exchange Server.
For each .bad file in BadMail folder there will be a corresponding .bdp and .bdr file.
Opening a bad file as simple as opening any other file formats, locate the .bad file and double click on it if the file is in healthy state then it will open immediately but if the BAD file is corrupted or damaged then you need to select the appropriate application that can open the damaged file.
If you are not able to open the .bad file then there will be some issue which is listed below.
Note: - You are suggested that always check weather the file is a malware or not while receiving from others. Otherwise opening the file will activate the malware.