"Could you please make an integration for …?”
Most likely, yes.
That is if the app you’re requesting an integration for has an available API end point, making an integration is possible.
You see most email softwares have API endpoints which lets apps like Socialscribe send them email addresses of people who sign up.
If your app does have an API endpoint, shoot me an email with your license key or the email address with which you bought Socialscribe and I’ll get the integration ready in 1-2 weeks.
PS: Substack doesn’t have any API endpoint available yet.