Custom Sender Email Configuration

I need help tweaking my current mail-sending setup so that every outgoing message shows a sender address on my own domain instead of the default one my system now adds. Nothing else in the message needs to change—just the “From” field must display the custom-domain email I provide. You’ll look at the code or service that dispatches the emails, adjust the SMTP or API settings accordingly, and verify that the new address appears correctly in major clients (Gmail, Outlook, Apple Mail) without triggering spam or spoofing warnings. SPF, DKIM, and DMARC records are already in place; update them only if the change requires it. Once finished, send me a short note describing what you modified and a test message that proves the new sender email is live and authenticated.