You can use git request-pull command to make a text output which can be sent to the project author in an email.

usage: git request-pull [options] start url [end]
    -p                    show patch text as well

example:

$ git request-pull b217fece9  https://gitlord.com/r/~dchem/hlsdump.git 
  Handles https requests as well as http (2015-07-30 16:17:10 -0700)
are available in the git repository at:
  https://gitlord.com/r/~dchem/hlsdump.git 
for you to fetch changes up to b217fece9a0ab76e82c494a8eb6bfa702546e218:
  Handles https requests as well as http (2015-07-30 16:17:10 -0700)

And then email this to the author.

Here's the full article that explains it all:

http://git-blame.blogspot.com/2012/01/using-signed-tag-in-pull-requests.html