added IMAP, LetsEncrypt, update layout

internal/dkim/dkim.go

@@ -216,6 +216,23 @@ func stripExistingSignature(content string) string {
 	return strings.Join(out, "\n")
 }
 
+// VerifyInbound checks whether content carries at least one valid DKIM signature
+// aligned to domainName (typically the From-header domain), mirroring Sign's
+// error-swallowing-to-false style. Used only as one signal feeding the inbound spam
+// heuristic (internal/mailstore) — never blocks delivery by itself.
+func VerifyInbound(content, domainName string) bool {
+	verifications, err := msgdkim.Verify(strings.NewReader(content))
+	if err != nil {
+		return false
+	}
+	for _, v := range verifications {
+		if v.Err == nil && strings.EqualFold(v.Domain, domainName) {
+			return true
+		}
+	}
+	return false
+}
+
 // GetActiveCustomHeaders mirrors DKIMManager.get_active_custom_headers.
 func (m *Manager) GetActiveCustomHeaders(domainName string) ([][2]string, error) {
 	dom, err := m.DB.GetDomainByName(domainName)