HOWTOs, tips and tricks

Start telnet:

telnet aspmx.l.google.com 25

Send local domain:

ehlo local.domain

Enter sender address:

mail from:<user@local.domain>

Enter recipient address:

rcpt to:<user@mail.com>

Enter mail body:

data
Subject: test
From: user@local.domain
Test message
.

Quit telnet:

quit