Unable to send e-mail i want to create a new user, for this , i have done the following things.
1.Installed SMTP module through drush
2.Installed sendmail through apt-get
3.and created the new user, when i trying to create a user it shows the error as mentioned in image.
Please someone help me to get out of it.
You dont necessary need the SSMTP module. 

I think this is a bad configuration with your local environment. For testing purpose you should consider using Gmail.


  Debian/Ubuntu users can Install with this command or click here to
  open up apt:
  
  sudo apt-get install ssmtp
  
  We need to then need to edit, ‘/etc/ssmtp/ssmtp.conf’:


root=username@gmail.com mailhub=smtp.gmail.com:587 rewriteDomain= hostname=username@gmail.com UseSTARTTLS=YES AuthUser=username AuthPass=password FromLineOverride=YES



  Then add each account that you want to be able to send mail from by
  editing, ‘/etc/ssmtp/revaliases‘:


root:username@gmail.com:smtp.gmail.com:587
localusername:username@gmail.com:smtp.gmail.com:587


If you do not want to used Gmail here is another tutorial with an alternative Sendgrid.