When you try to send a test message (assuming that the password is correct), you can get an error message that states that "Username and password not accepted". This is due to Google security policies that all third-party applications are unsafe
...
This could mean that your Google account does not have third-party app access enabled.
There are two ways to solve this problem:
Create app password (recommended)
Enable “Less secure app access”
Creating app password
To be able to create an “app password” you have to enable 2-Step Verification (you can read more here).
After you enabled 2-Step Verification do next:
Go to the “Security” section on the Google Account page.
Then navigate to the “App Passwords” page
On the page that opens choose “Mail” as an app and “Windows computer” as a device and press “Generate”
Copy the generated password and insert it as an Email password in the Mail service settings in ProjectMaker.
Enabling “Less secure app access”
In order to solve it, you need to do the following:
On the Google Account page open the section “Security”, find section “Less secure app access” and at the bottom of the page, follow the link "Turn on access"
On the page that opens, install the check box "Allow less secure apps"
After that, repeat the test sending of the mail. If everything is done correctly, then in the status bar you will see the "Test email has been sent successfully." message.
