I'm having the same issues here too. Email::setAdminEmail([email protected]'); is set in _config.php, yet the site still sends email with the from address set to [email protected].
I know this isn't hard coded anywhere, as the "sub" part in that address changes now and then. Must be some sort of email load balancing at my host.
2 Strange things:
1. setAdminEmail worked for a while, but as soon as I changed the recipient address in the CMS, it went back to this.
2. Last time it did this, it would eventually cease to send the emails at all (but still log the user's input)