Laravel - mailing campaign application: sending email from multiple domains intermittently

Description: -User Bob works at a company (let's take Disney as an example) and sends email to email groups. -Disney owns domains of different franchises, User Bob needs to be able to send a campaign from source email address noreply@[login to view URL] and later on the same day he needs to do a second mailing and switch to noreply@[login to view URL] from within the web interface. -Maybe tomorrow they buy a new domain [login to view URL], bob should be able to add the new domain in the web interface and send mail from that source email address. We are thinking something like input values and based on that a key is found in the config. -We can't use mailgun, mailchimp, gmail or any other 3d service. -Bob will not be the only one using this application. Alice works at Nestle, she also sends campaigns to different domains that Nestle owns, she should not be able to send from Bob's domains. These available domains should be tied to a GroupID. Restrictions/limitations: -The core component is the switching of domains. I need a working proof of concept (POC) for that, the POC doesn't even need to have login functionality (disregard Alice for the moment), it can send email to a group of only 2 email addresses. Preferably it would be simple for Bob/Alice to add a domain, otherwise it should not be to difficult for an admin (myself) to add this in a config. Expected result: -basic web interface, send test email to 2 from domain A. -Mail received from domain A. -Click dropdown, select domain B -send test email to 2 from domain B. -Mail received from domain B. Not in scope: -VPS with SMTP configured will be provided but it might take some time to set up. -Customers (bob) will have to set MX, SPF record in DNS records to not be flagged as spam. I will provide 2 domain names and deal with the DNS config. Requirements: -Freelancer must be willing to sign NDA and IP agreement -Explain to me how you would tackle this challenge and how long you expect it would take to create a POC.