fix: decode RFC 2047 encoded words in mail sender display name

apps/api/internal/app/maildir_sync.go

@@ -485,12 +485,58 @@ func partFilename(header textproto.MIMEHeader) string {
 func firstAddressParts(value string) (string, string) {
 	items, err := netmail.ParseAddressList(value)
 	if err != nil || len(items) == 0 {
-		return strings.TrimSpace(value), ""
+		// ParseAddressList failed — attempt RFC 2047 decode on the raw header,
+		// then retry parsing. This handles non-standard From headers where
+		// encoded words (e.g. =?UTF-8?B?…?=) cause the initial parse to fail.
+		decoded := decodeMIMEHeader(value)
+		items, err = netmail.ParseAddressList(decoded)
+		if err != nil || len(items) == 0 {
+			// Still unparseable: return the decoded value as the email and
+			// try to extract a display name from the decoded string.
+			email, name := splitNameAndEmail(decoded)
+			return normalizeEmail(email), strings.TrimSpace(name)
+		}
 	}
 	item := items[0]
 	return normalizeEmail(item.Address), strings.TrimSpace(item.Name)
 }
 
+// decodeMIMEHeader decodes all RFC 2047 encoded words (=?charset?encoding?data?=)
+// in the given header value. Falls back to the original value on any error.
+func decodeMIMEHeader(value string) string {
+	if !strings.Contains(value, "=?") {
+		return value
+	}
+	decoder := new(mime.WordDecoder)
+	decoded, err := decoder.DecodeHeader(value)
+	if err != nil {
+		return value
+	}
+	return decoded
+}
+
+// splitNameAndEmail attempts to extract a display name and email address from
+// a string like "Display Name <user@example.com>" or plain "user@example.com".
+func splitNameAndEmail(value string) (string, string) {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return "", ""
+	}
+	// Try "Name <email>" pattern
+	if idx := strings.LastIndex(value, "<"); idx > 0 {
+		email := strings.TrimRight(value[idx+1:], ">")
+		name := strings.TrimSpace(strings.Trim(value[:idx], `" `))
+		if strings.Contains(email, "@") {
+			return email, name
+		}
+	}
+	// Plain email or unknown format
+	if strings.Contains(value, "@") {
+		return value, ""
+	}
+	return value, ""
+}
+
 func addressList(value string) []string {
 	items, err := netmail.ParseAddressList(value)
 	if err != nil {

apps/web/src/pages/admin.tsx

@@ -810,10 +810,34 @@ function escapeHtml(value: string) {
   return value.replace(/[&<>"']/g, (char) => ({ "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" })[char] || char)
 }
 
+/**
+ * Decode RFC 2047 encoded words in mail headers (e.g. =?UTF-8?B?5byA5ZSu?=).
+ * Handles Base64 (B) and Quoted-Printable (Q) encoding.
+ */
+function decodeMimeHeader(value: string): string {
+  if (!value || !value.includes("=?")) return value
+  return value.replace(/=\?([^?]+)\?([bBqQ])\?([^?]*)\?=/g, (_match, charset, encoding, encoded) => {
+    try {
+      const lowerEncoding = String(encoding).toLowerCase()
+      let decoded: string
+      if (lowerEncoding === "b") {
+        decoded = atob(encoded)
+      } else {
+        decoded = encoded.replace(/_/g, " ").replace(/=([0-9a-fA-F]{2})/g, (_m: string, hex: string) => String.fromCharCode(parseInt(hex, 16)))
+      }
+      const bytes = new Uint8Array(Array.from(decoded, (ch) => ch.charCodeAt(0)))
+      const decoder = new TextDecoder(String(charset).toLowerCase() || "utf-8")
+      return decoder.decode(bytes)
+    } catch {
+      return _match
+    }
+  })
+}
+
 function adminSenderDisplayName(message: MailMessage) {
-  const fromName = message.fromName?.trim()
+  const fromName = decodeMimeHeader(message.fromName?.trim() || "")
   if (fromName) return fromName
-  const text = message.from.trim()
+  const text = decodeMimeHeader(message.from.trim())
   const namedAddress = text.match(/^"?([^"<]+?)"?\s*<[^>]+>$/)
   const name = namedAddress?.[1]?.trim()
   if (name) return name
@@ -822,8 +846,9 @@ function adminSenderDisplayName(message: MailMessage) {
 }
 
 function adminSenderTitle(message: MailMessage) {
-  const name = message.fromName?.trim()
+  const name = decodeMimeHeader(message.fromName?.trim() || "")
-  return name ? `${name} <${message.from}>` : message.from
+  const from = decodeMimeHeader(message.from)
+  return name ? `${name} <${from}>` : from
 }
 
 function Stat({ icon, label, value }: { icon: React.ReactNode; label: string; value: React.ReactNode }) {

apps/web/src/pages/mail.tsx

@@ -1293,6 +1293,31 @@ function MailboxSwitcher({ collapsed, mailboxes, selectedMailbox, onSelect }: {
   )
 }
 
+/**
+ * Decode RFC 2047 encoded words in mail headers (e.g. =?UTF-8?B?5byA5ZSu?=).
+ * Handles Base64 (B) and Quoted-Printable (Q) encoding.
+ * Returns the original string unchanged if no encoded words are found or on error.
+ */
+function decodeMimeHeader(value: string): string {
+  if (!value || !value.includes("=?")) return value
+  return value.replace(/=\?([^?]+)\?([bBqQ])\?([^?]*)\?=/g, (_match, charset, encoding, encoded) => {
+    try {
+      const lowerEncoding = String(encoding).toLowerCase()
+      let decoded: string
+      if (lowerEncoding === "b") {
+        decoded = atob(encoded)
+      } else {
+        decoded = encoded.replace(/_/g, " ").replace(/=([0-9a-fA-F]{2})/g, (_m: string, hex: string) => String.fromCharCode(parseInt(hex, 16)))
+      }
+      const bytes = new Uint8Array(Array.from(decoded, (ch) => ch.charCodeAt(0)))
+      const decoder = new TextDecoder(String(charset).toLowerCase() || "utf-8")
+      return decoder.decode(bytes)
+    } catch {
+      return _match
+    }
+  })
+}
+
 function cleanAccountName(name: string, email?: string) {
   const value = name.trim()
   if (!value || (email && value.toLowerCase() === email.toLowerCase())) return email?.split("@")[0] || "用户"
@@ -1306,13 +1331,13 @@ function accountInitial(name: string, email?: string) {
 }
 
 function senderDisplayName(message: MailMessage) {
-  const fromName = message.fromName?.trim()
+  const fromName = decodeMimeHeader(message.fromName?.trim() || "")
   if (fromName) return fromName
   return displayNameFromAddress(message.from)
 }
 
 function displayNameFromAddress(value: string) {
-  const text = value.trim()
+  const text = decodeMimeHeader(value.trim())
   const namedAddress = text.match(/^"?([^"<]+?)"?\s*<[^>]+>$/)
   const name = namedAddress?.[1]?.trim()
   if (name) return name
@@ -1322,8 +1347,9 @@ function displayNameFromAddress(value: string) {
 }
 
 function senderTitle(message: MailMessage) {
-  const name = message.fromName?.trim()
+  const name = decodeMimeHeader(message.fromName?.trim() || "")
-  return name ? `${name} <${message.from}>` : message.from
+  const from = decodeMimeHeader(message.from)
+  return name ? `${name} <${from}>` : from
 }
 
 function MessageRow({