Hi,
Using Netcam Studio with Google email has been problematic for some time due to increased security from Google which of cause is necessary. After May 30 Google close the use of what they call non-secure third party Apps. However, Google has come with a solution that they call Sign in with App Password. Here is a link to Google where they explain the process Sign in with App Passwords - Google Account Help
In short you turn on 2-step verification. Generate a 16 character App Password unique for NCS. In the email settings in NCS you enter all the usual information for your Google email account. For Password use the newly generated 16 character App password. Send a test message. That worked very fine for me.
-Henrik