“This email address does not exist or the password is incorrect.” This error generally occurs when the email address spelling might be wrong or the password mentioned is not correct. The user will have to check the password or reset the password to access the email address.
To resolve this,
Click on Forgot Password link on the page itself & follow the instructions.
Reset the password via an alternate email address/mobile number
If you are not able to reset the password then you need to contact your email administrator.
Admin can reset the password from the admin panel via Admin (Single User Management >> Change Password)