Issue with Mailx command

Shell Programming and Scripting
1

Hi,
I am trying to send an email using mailx command in Linux terminal. Though I give invalid address it is giving response as Recipient ok and sent message. My command is here. Not sure what is wrong. Can anyone please assist?

 echo -e 'New User'| mailx -v -s 'New User' y@gggg.com


>>> RCPT To:<y@gggg.com>
>>> DATA
250 2.1.5 <y@gggg.com>... Recipient ok
354 Enter mail, end with "." on a line by itself
>>> .
250 2.0.0 wAKKMHT6000787 Message accepted for delivery
y@gggg.com... Sent (wAKKMHT6000787 Message accepted for delivery)
Closing connection 
>>> QUIT
2

mailx cannot tell you if an address is good or not.