Send email center emails from the client's support email instead of support@pelcro.com

🔍 Problem Statement

As a client's subscriber, I receive Email Center notifications from support@pelcro.com instead of the client's support address, causing confusion and misdirected replies.

💡 User Story

• As a client admin, I want Email Center notifications sent from my brand's support email, so that subscribers recognize the sender and replies reach my support team.

🎯 Definition of Done (DoD)

• ✔ Given a site has a verified sender domain and support email, when an Email Center notification is sent, then the From address is the site's support email.

• ✔ Given a site's sender domain is not verified, when an Email Center notification is sent, then the Reply-To header is the site's support email.

• ✔ Given a client admin sets a sender email via [clarify endpoint], when the request succeeds, then the API returns the domain's SPF/DKIM verification status.

• ✔ This change will impact API and Email Center, specifically site sender settings and the Mandrill send pipeline.

• ✔ This solution will include the following limitations: custom From requires client DNS (SPF/DKIM) verification; unverified domains keep support@pelcro.com as From; Mailchimp and third-party ESP sends out of scope; per-template sender overrides [clarify].