Vtiger outgoing mail server setting for gmail user

Mail Server Settings (SMTP)
 
* Server Name
User Name youremail@gmail.com
Password your email password
From Email youremail@gmail.com
Requires Authentication?  

  if not working let`s try with this setting

Mail Server Settings (SMTP)
 
* Server Name
User Name
Password
From Email youremail@yourcompany.com
Requires Authentication?

no need to use user name also password , and finaly don`t enable authentication