Hi Perry,

From my understanding, your colleague send an email with a rar file attached that contains a batch file (.bat), when you receive the file, the .bat file has been removed and replaced with a text file, you would like to get the .bat file back. Am I correct?

In this situation, the .bat file was blocked by our Exchange server by default, for higher security. Therefore, unfortunately, you would not be able to get the file back.

As a workaround, I suggest have your colleague change the suffix of the .bat file, and re-send the attachment.

In addition, we would be able to check our Outlook Web App Mailbox Policies and change it, in this way, we can prevent the certain file type been blocked.
You can refer to the following steps:
1), Install and Configure Windows PowerShell.
2), Run the following command:
Run “ Get-OwaMailboxPolicy ” and note the BlockedMimeTypes, AllowedMimeTypes.
Run “ Set-OwaMailboxpolicy “ to change the blocked and allowed filetypes.

For more information, please refer to the following pages:
Manage Outlook Web App Features Using Outlook Web App Mailbox Policies

If you need any further help, please don’t hesitate to contact us.

Best Regards,
Evan Zhang