First Create a mailing list within 300 email, not more than. After create a new campaign you will redirect to campaign settings , here under SMTP settings set the below mentioned data. Delay between sending emails from SMTP :- 30 SECOND SMTP Server Address :- smtp.mail.yahoo.com From mail id :- your yahoo mail id (yourmail@yahoo.com) Mail login id :- your yahoo mail id (yourmail@yahoo.com) Mail login id :- your yahoo mail password/less secure password (please see the details below) port :- 465 SSL :- enable TLS :- disable Compleate all settings, first put your normal Yahoo login password into password field then click on "Test Connection" button, it will send a mail to our server if everything is correct then you will get success message eithir you will get SMTP error message. If you get error then first (1)Log into your Yahoo email account from browser (2)Click your name on top right (3)Click the text 'Account info' (4)Click 'Account Security' from left panel (it will ask agin for login) (5) see the below of the page 'App password' under Other ways to sign in (6) Click on 'Generate and manage App password' (7) put the name of app PD MASS MAILER and generate password. Then copy this password and paste it into your login password field and again click on TEST Connection Button. After success set other field like mail subject , from name , select mailing list, then click on 'SAVE' button to save your settings and write your html mail body.