If you are using an email address hosted by Google (Gmail, G-Suite, etc) and want to use that email from the email sending configuration in your site manager, you need to change your Google account's security settings first, before configuring your eDirectory.
1) Sign in to your email account and go to this page: https://myaccount.google.com/security
2) Scroll the page and find the “Signing in to Google” section.
3) Then, turn off "Use your phone to sign in" and "2-Step Verification".
4) Scroll and find the “ Less Secure App Access” section
5) Turn ON Less Secure App Access
6) Now navigate to https://accounts.google.com/DisplayUnlockCaptcha and click Continue
7) After making these changes, login into your Site Manager and click on Settings > Email Sending Configurations. There you can enter the information like below.
Check the option "The server above requires secure authentication (TLS/SSL)"
Email Address: here you put your email address ex; firstname.lastname@example.org
Username: here you put your email address again. It should match the email address you put above.
Password: here you put the password of your email address
8) Hit “Save Configurations”.