Install smtpprox by entering the following commands in the terminal:
sudo apt update sudo apt install smtpprox
Description:
simple efficient SMTP proxy in perl
smtpprox is a trivial transparent SMTP proxy, an SMTP server and client combination. . The SMTP server writes the incoming message to a temporary file, which the SMTP client reads as the message to send. SMTP commands and replies are relayed without change for the most part. . For efficiency reasons, it pre-forks and serves from a pool of servers, Apache-style.
Homepage: http://bent.latency.net/smtpprox/
Version: 1.2-1
Section: universe/mail