In an effort to protect users from potential email problems like viruses, malicious scripts, etc., Microsoft Started blocking certain file types from being opened or executed beginning with Outlook 2000. With the release of Outlook 2010 the number of file types has grown considerably. While this can be a good idea there may be occasions when we want to open an attachment such as one a friend may have sent. That's where Outlook Attachments can help. Operation is very simple. If you receive an attachment that is blocked close Outlook, use Outlook Attachments to allow the file type, ReOpen Outlook and the file will now be available.
You can also add your own file types to be blocked or allowed. For instance if there are other file types you want to be blocked such as Photos and MP3 files just add the file extensions jpg and mp3 to the blocked list. You can move them to the allowed list any time if there's one to you want to open.