Email sending using send-mail - Ubuntu 14.04

I have tried to send email usgin below command

mail -s "Subject" [email protected]

I have received the below error from command line.

root@lc:/home/dasitha# send-mail: authentication failed (method PLAIN) send-mail: server message: 534-5.7.14 Please log in via your web browser and send-mail: server message: 534-5.7.14 then try again. send-mail: server message: 534-5.7.14 Lea more at send-mail: server message: 534 5.7.14 https://support.google.com/mail/answer/78754 x5sm554067pax.33 - gsmtp send-mail: could not send mail (account default from /root/.msmtprc)

Kindly help me on this.

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