@RaviDevaraj, Two things you need to check,
- Confirm that you have entered the right credentials
- If you have configured your account for two - step verification then you need to provide the password [one time] that you have generated.
References:
- "Authentication Failed" when using SMTP Mail Message Activity - #5 by mircea
- "Authentication Failed" when using SMTP Mail Message Activity - #7 by ovi
- Send smtp mail not working - #5 by rahatadi
Regards,
Dom