feat: Move mail system to shared

shared/mail/contact.go

@@ -0,0 +1,27 @@
+package mail
+
+import "time"
+
+// Enquiry is one submission of the public site's contact form.
+type Enquiry struct {
+	Name    string
+	Email   string
+	Servers string
+	Topic   string
+	Message string
+}
+
+// SendEnquiry forwards a contact-form submission to the support address.
+//
+// Reply-To is the sender's address, not From: the message is sent by our own
+// SMTP identity so it passes SPF, but hitting reply must reach the person who
+// filled the form in.
+func (s Sender) SendEnquiry(to string, e Enquiry) error {
+	return s.sendTemplate(to, e.Email, "contact", struct {
+		Enquiry
+		Received string
+	}{
+		Enquiry:  e,
+		Received: time.Now().UTC().Format(time.RFC1123),
+	})
+}