Below is the example file for you to configure the hawkagent.cfg files for gmail:

# Email Action configuration
# SMTP server host name
-email_smtp_server smtp.gmail.com

# SMTP server port, default value is 25.
-email_smtp_port 465

# Whether SMTP server authentication is required or not, default value is false.
-email_smtp_auth_required true

# Whether SMTP server requires TLS or not, default value is false.
# Note : some providers like gmail have started enforcing TLS
#        user need to review blocked sign-in attempts and change security policy
#        for the email that is being used
-email_smtp_tls_required true

# SMTP socketFactory port needed for TLS, default value is 25.
-email_smtp_socket_factory_port 465

# SMTP server user name
# Required only if SMTP server authentication is configured true.
-email_smtp_user <UserName>

# SMTP server user password.
# Required only if SMTP server authentication is configured true.
-email_smtp_password <Password>

# Email From (Email Sender)
# Optional, default is current system user
-email_from <Sender email address>

# Email Content-Type
# Optional, default value is text/html
#-email_content_type

-Please customize your hawkagent.cfg file as given above and you will able to send the mail.

-After sending the mail you will receive an mail from google.suggesting "Review blocked sign-in attempt".

-Please allow it to receive an mail which you will sent.

-Please try to turn "Less secure app access" on if still cannot send email successfully.
https://myaccount.google.com/lesssecureapps