have added attached config in my SMTP settings, but while trying to send email for user registration it always shows 
Note: have enabled less secure app login on gmail as well
I personally don't use Gmail, but there is this page in the MoodleDocs https://docs.moodle.org/310/en/Email_setup_gmail.
thanks for the reply Visvanath, had followed the same link but still not working
had tried tls too.
Finally it worked.. Config is fine.. tried a sample test code for smtp with gmail first.. which highlighted the changes to be done in gmail. post that this worked fine.
In reply to Varun Aggarwal
Re: Moodle 3.10 gmail SMTP not working [RESOLVED]
by Visvanath Ratnaweera -
Good work! Is that testing method not documented under https://docs.moodle.org/310/en/Email_setup_gmail ?