Hi @Barback,
This is default WordPress functionality and not anything that our plugins change or set up – the reason is because our plugins simply use the “wp_mail()” function that is included within WordPress Core. The default “address” for your site’s mailing function is wordpress@[your-site].com
If you’re interested in this function, check out this Codex page about it → https://codex.wordpress.org/Function_Reference/wp_mail
To change things like the “from” address and such, you would have to use custom code on this function or use other plugins to change settings.
I hope this information helps shed some light on this; let me know if that’s the case and/or if you have any other questions!
Cheers,
George