Question

I had written a program (In Android, client side and PHP, server side) to upload a file to a server over HTTP. Due to various reasons I had to change the system to do everything in SSH (for security among other things).

I have the basics set up (using jsch on Android). But I want to implement the equivalent of the PHP mail() function. When the file is uploaded, originally my PHP file automatically sends a mail from the server to a certain address.

I’m struggling to find a way to implement this within a shell on the server. So the question is, how do I automatically send an email from server in SSH?

EDIT:
Forgot to mention server is CentOS.

Answer 1

SSH itself has no mail function – it only supports shell access (which might include X and SSH agent forwarding), file transfer (or other subsystems that might be integrated into the server) and port forwarding.

So, you have basically these options:

• Call some server-side shell command that causes the mail to be sent, as mentioned in the comment from Marc.
  This would use a shell channel.

• Use port forwarding to access an SMTP server on your server host (or any host that accepts mail from there).

  If you want to send from the same program which uses JSch, there is no need to actually do client-side
  port forwarding, instead simply use a direct-tcpip channel, and set its host and port properties
  before connecting.

  Then you’ll have to implement the SMTP protocol yourself, or use any other library which supports SMTP. (I suppose JavaMail can do this, but I didn’t explore how you can configure it to use JSch as a tunnel.)