How to OPEN a file that is in an array of bytes?

Question

The situation is as follows: I have a database where I store some files in bytes array (these files are OUTLOOK E-MAILS of the extension .msg). The purpose of this is nothing more than this:

When I click there on open attachment I just want it to transform the byte[] into file again and open the file so I can forward the email ... this kind of thing.

Language C#