[anonymousiam]

Back in the day, you could do similar things with a .forward file. I once wrote a script using a .forward file, "expect", "telnet", and "pppd" that would bring up a VPN into my company when I sent a crafted email to my work account.

The corporate IT folks had a pretty good firewall and dialup VPNs, but they also had a "gauntlet" BSD machine that one could use to directly access Internet hosts. So upon receiving the activation email, my script connected to the BSD proxy, then used telnet to reach my Internet host on a port with a ppp daemon listening, and then detached the console and connected it to a local (from the corporate perspective) ppp daemon. Both ppp daemons were configured to escape the non-eight-bit-clean characters in the telnet environment.

I used this for years, because the connection was much faster than the crummy dialup VPN.

I immediately dismantled it when my company issued updated IT policies which prohibited such things. (This was in the early 1990's.)

https://www.cs.ait.ac.th/~on/O/oreilly/tcpip/sendmail/ch25_0...