Qmail: send email from shell
 

How to send an email from shell using qmail 'mail' function?

from the TEST.deliver file that comes with the qmail install files

3. Local-local test: Send yourself an empty message. (Replace ``me''
with your username. Make sure to include the ``to:'' colon.)
% echo to: me | /var/qmail/bin/qmail-inject
The message will show up immediately in your mailbox, and syslog
will show something like this:
qmail: new msg 53
qmail: info msg 53: bytes 246 from <me@domain> qp 20345 uid 666
qmail: starting delivery 1: msg 53 to local me@domain
qmail: status: local 1/10 remote 0/20
qmail: delivery 1: success: did_1+0+0/
qmail: status: local 0/10 remote 0/20
qmail: end msg 53
(53 is an inode number; 20345 is a process ID; your numbers will
probably be different.)