Is the album in your phone's memory, or uploaded to a cloud service, like Google Plus, Picasa or Dropbox? What you want to do is best done from a cloud service. In either the gallery app or the cloud service app, you can usually press and hold the album and choose the Share button.
Or you could zip the folder (an album in Gallery is a folder in storage) and send the zip file if it's small enough. (You can't email an album - it's just a list of files.)