Preserve QOutlook priority headers in EML

src/io/outlookMail.ts

@@ -91,6 +91,7 @@ export async function importEmlFile(file: File): Promise<ImportedMailMessage> {
     ...(parsed.headers.bcc ? { bcc: decodeMimeWords(parsed.headers.bcc) } : {}),
     ...(parsed.headers["reply-to"] ? { replyTo: decodeMimeWords(parsed.headers["reply-to"]) } : {}),
     ...mailThreadHeaders(parsed.headers),
+    ...mailPriorityHeaders(parsed.headers),
     subject: decodeMimeWords(parsed.headers.subject || "Без темы"),
     body: extractMessageBody(parsed.headers, parsed.body),
     time: parsed.headers.date || new Date().toLocaleString("ru-RU"),
@@ -129,6 +130,7 @@ export function msgDataToMailMessage(reader: Pick<MsgReaderInstance, "getAttachm
     ...(bcc ? { bcc } : {}),
     ...(replyTo ? { replyTo } : {}),
     ...mailThreadHeaders(headerFields),
+    ...mailPriorityHeaders(headerFields),
     subject: firstText(data.subject, decodeMimeWords(headerFields.subject || ""), "Без темы"),
     body: msgBodyText(data),
     time: firstText(data.messageDeliveryTime, data.clientSubmitTime, data.creationTime, data.lastModificationTime, headerFields.date, new Date().toLocaleString("ru-RU")),
@@ -424,6 +426,7 @@ export function buildEmlSource(message: MailMessage): string {
       `Subject: ${encodeHeaderValue(message.subject || "Без темы")}`,
       `Date: ${sanitizeHeaderValue(message.time || new Date().toUTCString())}`,
       ...optionalThreadHeaders(message),
+      ...optionalPriorityHeaders(message),
       "MIME-Version: 1.0",
       `Content-Type: multipart/mixed; boundary="${boundary}"`,
       "",
@@ -447,6 +450,7 @@ export function buildEmlSource(message: MailMessage): string {
     `Subject: ${encodeHeaderValue(message.subject || "Без темы")}`,
     `Date: ${sanitizeHeaderValue(message.time || new Date().toUTCString())}`,
     ...optionalThreadHeaders(message),
+    ...optionalPriorityHeaders(message),
     "MIME-Version: 1.0",
     "Content-Type: text/plain; charset=utf-8",
     "Content-Transfer-Encoding: 8bit",
@@ -485,6 +489,26 @@ function mailThreadHeaders(headers: MailHeaders): Pick<MailMessage, "messageId"
   };
 }
 
+function optionalPriorityHeaders(message: MailMessage): string[] {
+  return [
+    ...(message.importance?.trim() ? [`Importance: ${sanitizeHeaderValue(message.importance)}`] : []),
+    ...(message.xPriority?.trim() ? [`X-Priority: ${sanitizeHeaderValue(message.xPriority)}`] : []),
+    ...(message.priority?.trim() ? [`Priority: ${sanitizeHeaderValue(message.priority)}`] : [])
+  ];
+}
+
+function mailPriorityHeaders(headers: MailHeaders): Pick<MailMessage, "importance" | "xPriority" | "priority"> {
+  const importance = sanitizeHeaderValue(headers.importance || "");
+  const xPriority = sanitizeHeaderValue(headers["x-priority"] || "");
+  const priority = sanitizeHeaderValue(headers.priority || "");
+
+  return {
+    ...(importance ? { importance } : {}),
+    ...(xPriority ? { xPriority } : {}),
+    ...(priority ? { priority } : {})
+  };
+}
+
 export function decodeMimeWords(value: string): string {
   return value
     .replace(/(=\?[^?]+\?[bqBQ]\?[^?]+\?=)\s+(?==\?[^?]+\?[bqBQ]\?[^?]+\?=)/g, "$1")