This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
What is the "it" in "it allows to browse gallery only"? If you want to use the email client's attachment feature for arbitrary files stored on your device then you need to install an application that allows you to browse all files - something like OI File Manager, or any of a number of file managers available.
If, on the other hand, you're trying to attach the file to the intent you're creating, then something like this should work: