After SQLMessenger is installed, we need to configure email accounts within it for sending emails.
Unlike other email services, configuring Gmail and Yahoo Mail accounts requires entering the App Password as the login password for the email account, instead of the Gmail or Yahoo account password.
Gmail Email Account Config
Step1: Log in to your Google account, then click the "Account" icon on the Google menu.

Step2: Enter "App Password" in the "Search Google Account" field, then click on the "App Passwords Security" option.

Step3: Enter a "App Name" for the new App Password, then click the "Create" button

Step4: After successfully creating the password, Google will display the new password on the page. Please enter this password in the SQLMessenger's "App Password" text box.

Yahoo Email Account Config
Step1: Log in to Yahoo Mail in your browser, then click the "Account info" icon.

Step2: Click "Security" on the page.

Step3: On the page, locate to the "App Passwords" and click "Generate App Password".

Step4: Enter "App Name", then click "Generate Password".

Step5: After successfully creating your password, Yahoo will display it on the page. Please enter this password in the SQLMessenger's "App Password" text box.

Reposted from: http://www.sqlmessenger.com/manual/index.htm?page=5.htm