Server Address: smtp.gmail.com
Username: Your Gmail Address (e.g. [email protected])
Password: Your Gmail Password
Port Number: 587 (With TLS)
Alternative Port Number: 465 (With SSL)
Internet Protocol: Dynamic IPs Allowed
Sending Limits: A registered G Suite user can’t relay messages to more than 10,000 recipients per day.

To make Gmail more secure, Google has added an extra layer of protection to Gmail accounts. When a third party server tries to read or enter into your Gmail account and it gets blocked by Google servers if their security is not upto Google’s level.
So, before you go on and start the configuration, make sure that Less Secure Apps option is enabled for the desired account in Gmail.
Generally, it is not recommended to enable “Less Secure Apps” option as it comes with certain risks to your Gmail account. So, it is advisable to use this when no other option is available.
To enable Less Secure Apps, You can visit this link. It will look something like this:

There is one other catch. And for security reasons, if you have enabled Google’s “Two Step Verification” process for your Gmail account then you won’t be able to enable the option of “Less Secure Apps”.
With “Two Step Verification” option enabled, the “Less Secure Apps” page will look something like this:

To enable “Less Secure Apps”, You will have to disable “Two Step Verification” for your Gmail account. After that, you can easily enable the “Less Secure Apps” option.

Gmail SMTP Settings