A simple and quite dummy smtp server which store every received email to a file.
Files are stored as-is in the current directory by default.
Type python dummysmtpd.py --help for more options.
Type python dummysmtpd.py to start the server.
In another terminal, connect to the server using nc and type the following <-prefixed lines:
$ nc localhost 1025
> 220 localhost Python SMTP proxy version 0.2
< HELO localhost^M
> 250 localhost
< MAIL FROM: nicolas@test.com^M
> 250 Ok
< RCPT TO: test@test.com^M
> 250 Ok
< DATA^M
> 354 End data with <CR><LF>.<CR><LF>
< Hello World!^M
< .^M
> 250 Ok
< QUIT^M
$
Note: Press Ctrl-V, then Enter to output a CRLF sequence, (^M in the example).