diff --git a/src/commands/openclaw.ts b/src/commands/openclaw.ts
index 868e9e5..9d04c90 100644
--- a/src/commands/openclaw.ts
+++ b/src/commands/openclaw.ts
@@ -467,15 +467,20 @@ openmail send --to "recipient@example.com" --subject "Report" --body "<p>See att
 
 \`--body\` accepts plain text or HTML — HTML is detected and rendered automatically.
 
-Add \`--attach <path>\` to attach files (repeatable). The response includes
-\`messageId\` and \`threadId\` — store \`threadId\` to continue the conversation
-later. Subject is ignored when replying in a thread.
+Add \`--attach <path>\` to attach files (repeatable). Add \`--cc <email>\` (repeatable)
+to copy other recipients. The response includes \`messageId\` and \`threadId\` — store
+\`threadId\` to continue the conversation later. \`--subject\` is optional when
+\`--thread-id\` is set — the thread subject is used automatically.
 
 **Always reply in the existing thread.** When the user asks you to reply
 to an email, look up the thread with \`openmail inbox\` or
 \`openmail threads list\` first, then use \`--thread-id\`. Never create a
 new thread unless the user explicitly asks for one.
 
+**When you were CC'd:** check \`deliveryRole\` and \`headerTo\` on the inbound
+message (via \`threads get\`). If \`deliveryRole\` is \`cc\`, reply to \`headerTo\`
+— not to \`fromAddr\`. OpenMail auto-CCs \`fromAddr\` on thread replies.
+
 ## Checking for new mail
 
 **Always use \`threads list --is-read false\` to check for new mail.**
@@ -527,6 +532,10 @@ Each message has:
 | \`id\` | Message identifier |
 | \`threadId\` | Conversation thread |
 | \`fromAddr\` | Sender address |
+| \`toAddr\` | Envelope recipient (your inbox address on inbound) |
+| \`headerTo\` | Who the sender addressed in the To header (use for CC replies) |
+| \`deliveryRole\` | \`to\` or \`cc\` — primary recipient vs CC'd |
+| \`cc\` | CC recipients |
 | \`subject\` | Subject line |
 | \`bodyText\` | Plain text body (use this) |
 | \`attachments\` | Array with \`filename\`, \`url\`, \`sizeBytes\` |
diff --git a/src/commands/send.ts b/src/commands/send.ts
index 6720398..1a39922 100644
--- a/src/commands/send.ts
+++ b/src/commands/send.ts
@@ -48,11 +48,12 @@ export async function runSendCommand(
   const noQuote = getBooleanFlag(parsed.flags, "no-quote");
   const idempotencyKey = getStringFlag(parsed.flags, "idempotency-key");
   const replyTo = getStringFlag(parsed.flags, "reply-to");
+  const cc = getRepeatedStringFlag("cc");
   const attachPaths = getRepeatedStringFlag("attach");
 
   if (!inboxId) throw new Error("missing inbox id; run `openmail init` or pass --inbox-id");
   if (!to) throw new Error("missing --to");
-  if (!subject) throw new Error("missing --subject");
+  if (!threadId && !subject) throw new Error("missing --subject (optional when --thread-id is set)");
   if (!body) throw new Error("missing --body");
 
   let attachments: { path: string; filename: string; contentType: string }[] | undefined;
@@ -80,13 +81,14 @@ export async function runSendCommand(
   return client.sendEmail({
     inboxId,
     to,
-    subject,
+    subject: subject ?? "",
     body,
     bodyHtml,
     threadId,
     includeQuote: noQuote ? false : undefined,
     idempotencyKey,
     replyTo,
+    cc: cc.length > 0 ? cc : undefined,
     attachments,
   });
 }
diff --git a/src/index.ts b/src/index.ts
index 12ebfd7..144d6c4 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -361,14 +361,16 @@ function printHelp(topic?: string) {
         "openmail send",
         "",
         "Usage:",
-        "  send --to <email> --subject <text> --body <text> [--inbox-id <id>]",
+        "  send --to <email> --body <text> [--subject <text>] [--inbox-id <id>]",
         "       [--thread-id <id>] [--no-quote] [--idempotency-key <key>]",
-        "       [--reply-to <email>] [--attach <file>]",
+        "       [--reply-to <email>] [--cc <email>] [--attach <file>]",
         "",
         "Options:",
+        "  --subject <text>    Required for new threads; optional with --thread-id",
         "  --body <text>       Plain text or HTML (HTML is auto-detected and rendered)",
         "  --thread-id <id>    Reply in a thread; quotes the previous message by default",
         "  --no-quote          Send only your reply text (skip auto-quoted history)",
+        "  --cc <email>        CC recipient (repeatable)",
         "  --reply-to <email>  Address replies should go to. Free plan: must be the",
         "                      address of an inbox you own. Developer+: any address.",
         "  --attach <file>     Attach a file (repeatable for multiple files)",
diff --git a/src/lib/http.ts b/src/lib/http.ts
index 8026a21..651c8fa 100644
--- a/src/lib/http.ts
+++ b/src/lib/http.ts
@@ -65,6 +65,7 @@ export class OpenMailHttpClient {
     includeQuote?: boolean;
     idempotencyKey?: string;
     replyTo?: string;
+    cc?: string[];
     attachments?: { path: string; filename: string; contentType: string }[];
   }) {
     const idempotencyKey = params.idempotencyKey ?? crypto.randomUUID();
@@ -82,6 +83,9 @@ export class OpenMailHttpClient {
         formData.append("includeQuote", "false");
       }
       if (params.replyTo) formData.append("replyTo", params.replyTo);
+      if (params.cc?.length) {
+        for (const addr of params.cc) formData.append("cc", addr);
+      }
 
       for (const att of params.attachments) {
         const data = await readFile(att.path);
@@ -96,7 +100,7 @@ export class OpenMailHttpClient {
       });
     }
 
-    const payload: Record<string, string | boolean> = {
+    const payload: Record<string, unknown> = {
       to: params.to,
       subject: params.subject,
       body: params.body,
@@ -105,6 +109,7 @@ export class OpenMailHttpClient {
     if (params.threadId) payload.threadId = params.threadId;
     if (params.includeQuote === false) payload.includeQuote = false;
     if (params.replyTo) payload.replyTo = params.replyTo;
+    if (params.cc?.length) payload.cc = params.cc;
 
     return this.post(url, payload, {
       "Idempotency-Key": idempotencyKey,