I have a prpaid Net-10 Nokia 1600, which is a very basic phone that can text and call people, and not much else. I could use it to recieve emails sent to my gmail account, but I couuldn't reply, but with a bit of googling and some inspiration from Popular Science I discovered this.
Step 1: Send the message
It should look someting like:
firstname.lastname@example.org (space) type your message here.
Except that the email address and message will be different and you don't spell out space.
and send it to 33715 (teleflip)
It should show up in your email within a few seconds.