File Extension UNK

UNK files are very rare files and one does not encounter these files in every day. UNK stands for UNKNOWN and that is a good indicator of what these files are. These files are produced by the Microsoft Mail program. Microsoft Mail is a Microsoft product that is the successor of the Microsoft Outlook application and it virtually identical to it in most respects. It allows users to read mails via IMAP or POP mails and also send mails using SMTP protocol. When the Microsoft Mail software receives a mail with an attachment that it was unable to identify, probably because the file was corrupt and not transferred properly, it converts the files into .UNK files. These conversions usually takes place when the original file was not passed across someone's gateway properly due to either security reasons or company policies which disallow those kind of files to be distributed within the network, sometimes these conversions are also done on files that are simply too large beyond the threshold limit of the common gateway. Once a file has been corrupted and converted into an .UNK file then there is no way of recovering the original file or reading its contents.