Question

I am really unsure as to where I should be posting this, but if this is the wrong place could someone direct me where to I could get an answer? I want to be able to send commands to my email address, and have the commands parsed and executed when the message is sent. I.e. I send an email and it contains this:

  public class sentThruEmail {
      public static void main(String[] args) {
          System.out.println("Hello");
      }
  }

I would want to configure my program to recognize when a new email comes from a sent address, to open it, compile it (in this case compile the java) and then execute it on the machine that the program is running on.
How can I go about figuring out how to do this? Any help would be wonderful, thanks!

EDIT: Or maybe the first step would be how to recognize an email was received from an address at all? In Java, how could I go about that: recognizing that an email was received and outputting something to the screen to alert the fact.

Answer 1

There are several parts of this to consider:

Security

As others mention, there are security risks to consider, here. If that worries you (and it should!), you may want to consider some of the following:

• Digitally signing these “command” emails, and verifying that signature before looking at the email
  • PGP is a popular choice for this
• Running your program (which reads the emails) in a “sandbox” environment, such as being chroot‘ed or in a jail
• Only run a very limited set of commands – perhaps just ones you invent.

Getting Mail

If you still want to do this, given the security issues, you will need your program to read mail.

You probably want to use IMAP for this, or POP.

Parsing

Once you have the mail, you need to parse the contents.
You could just compile it directly if you are only sending code.
You could also send the code as an attachment with a certain MIME type to identify it. That way you could still send a ‘normal’ email (perhaps with commentary about what this code is for), but your program would be able to cleanly separate out the code.

Responding

How will you communicate results back? Or do you care?

You may want to send a reply email (use SMTP), or update a webpage. A webpage is nice since if you are running the web server locally, you can just write a file directly.

Examples

• The standard “confirmation email” system has a lot of similarity to what you describe. Someone sends an email to an automated system, it reads it, does some processing, and replies. Search around for those systems and I’m sure you’ll get started.

• I created the Exquisite Corpse Emailer project, which does much of what you describe (but in Perl). It only accepts a very small set of limited commands, but it listens to an email address on IMAP, parses the text, updates a database as a result, etc.