I have a number of hosted webforms (using the webform module) that get integrated into client sites via iframes. I'm also using SMTP Authentication with a sending domain of smtp.webformhostsite.com, which is my server. When I set up each webform, I'd like to set the webform up so that sending email address is info@customersite.com, where customersite is the site where the form is hosted on.
I know I can just enter that email address in as the from address, but I'm concerned that the email is going to get flagged as spam or phishing as the send domain and the actual domain that is sent from aren't the same.
I believe there is a way that the customer can create MX records on their DNS servers that would validate smtp.webformhostsite.com as a valid sending domain for customersite.com, but I'm not aware of how to go through that process.
Can anybody provide any details or sources of how I would work to get this configured correctly?