Testing SMTP Server from the windows command line

C:\Users\Administrator>telnet relay.mx.testserver.com 25

220 mb1relay1.mx.testserver.com ESMTP
helo test
250 mb1relay1.mx.testserver.com
mail from: usename1@mail.com
250 sender <usename1@mail.com> ok
rcpt to: usename2@mail.com
250 recipient <usename2@mail.com> ok
data
354 go ahead
Hi How are you
.
250 ok:  Message 258249 accepted
quit
221 mb1relay1.mx.testserver.com


Connection to host lost.

Ref :- https://www.youtube.com/watch?v=lfYtz3uRPYc

Nullifying a log file

Clear a file using /dev/null 

/dev/null is often referred to a black hole in Linux based systems. It discards all the data written to it and sends EOF (End of File) character to any process reading data from it. With this logic, we can clear the contents of a file.

cp /dev/null logfile

cat /dev/null > logfile

> logfile

dd if=/dev/null of=logfile

Clear a file using truncate

truncate logfile --size 0