diff --git a/components/email/__tests__/quoted-html.test.ts b/components/email/__tests__/quoted-html.test.ts
new file mode 100644
index 000000000..6dbdea83f
--- /dev/null
+++ b/components/email/__tests__/quoted-html.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'vitest';
+import { Editor } from '@tiptap/core';
+import StarterKit from '@tiptap/starter-kit';
+import { buildQuotedHtmlBlock, QuotedHtml, serializeEditorContent } from '../quoted-html';
+
+const createEditor = (content: string) => new Editor({ extensions: [StarterKit, QuotedHtml], content });
+
+describe('HTML quote borders', () => {
+  it('keeps normal quote styling by default', () => {
+    const original = '<blockquote>Original reply</blockquote>';
+    const editor = createEditor(buildQuotedHtmlBlock(original));
+    try {
+      expect(editor.view.dom.querySelector<HTMLElement>('.quoted-html-island')?.style.borderLeftWidth).toBe('2px');
+      expect(serializeEditorContent(editor)).toContain(original);
+    } finally { editor.destroy(); }
+  });
+
+  it('flattens nested quotes and preserves content and border preference after reopening', () => {
+    const original = '<blockquote style="border-left:2px solid gray">Ok no problem<hr><blockquote>Hello this is a quick test<br><a href="mailto:max@example.com">Max</a></blockquote></blockquote><table><tbody><tr><td>Layout</td></tr></tbody></table>';
+    const editor = createEditor(buildQuotedHtmlBlock(original, { showQuoteBorder: false }));
+    let saved = '';
+    try {
+      const island = editor.view.dom.querySelector<HTMLElement>('.quoted-html-island')!;
+      expect(island.style.borderLeftWidth).toBe('');
+      expect(island.style.paddingLeft).toBe('');
+      expect(island.shadowRoot?.querySelector('blockquote')).toBeNull();
+      expect(island.shadowRoot?.textContent).toContain('Ok no problem');
+      expect(island.shadowRoot?.querySelector('a')?.getAttribute('href')).toBe('mailto:max@example.com');
+      expect(island.shadowRoot?.querySelector('td')?.textContent).toBe('Layout');
+      saved = serializeEditorContent(editor);
+      expect(saved).toContain('data-quote-border="false"');
+      expect(saved).not.toContain('blockquote');
+    } finally { editor.destroy(); }
+    const reopened = createEditor(saved);
+    try {
+      expect(reopened.view.dom.querySelector<HTMLElement>('.quoted-html-island')?.style.borderLeftWidth).toBe('');
+      expect(serializeEditorContent(reopened)).toBe(saved);
+    } finally { reopened.destroy(); }
+  });
+});
diff --git a/components/email/email-composer.tsx b/components/email/email-composer.tsx
index 81e641f48..6433a6c92 100644
--- a/components/email/email-composer.tsx
+++ b/components/email/email-composer.tsx
@@ -699,7 +699,7 @@ export function EmailComposer({
         // first; cid rewrite runs after so its data-cid markers survive).
         const island = buildQuotedHtmlBlock(
           rewriteCidImagesForEditor(sanitizeEmailHtml(replyTo.htmlBody)),
-          { remoteAllowed: quoteRemoteAllowed },
+          { remoteAllowed: quoteRemoteAllowed, showQuoteBorder: replyTo.quoteWrapInBlockquote !== false },
         );
         return `${prefix}${signatureBlock}<br>${replyTo.quoteHeaderHtml}${island}`;
       }
diff --git a/components/email/quoted-html.ts b/components/email/quoted-html.ts
index b983539b3..ad92c90bf 100644
--- a/components/email/quoted-html.ts
+++ b/components/email/quoted-html.ts
@@ -61,6 +61,11 @@ export const QuotedHtml = TiptapNode.create({
 
   addAttributes() {
     return {
+      showQuoteBorder: {
+        default: true,
+        parseHTML: (el) => el.getAttribute("data-quote-border") !== "false",
+        renderHTML: (attrs) => attrs.showQuoteBorder === false ? { "data-quote-border": "false" } : {},
+      },
       html: {
         default: "",
         // Capture the verbatim inner HTML when parsing. Because the node is
@@ -138,7 +143,11 @@ export const QuotedHtml = TiptapNode.create({
       const dom = document.createElement("div");
       dom.setAttribute(QUOTED_HTML_MARKER, "");
       dom.className = "quoted-html-island";
-      dom.style.cssText = QUOTE_BAR_STYLE + QUOTE_ISLAND_CONTAINMENT_STYLE;
+      const updateQuoteStyle = (showBorder: boolean) => {
+        dom.style.cssText = (showBorder ? QUOTE_BAR_STYLE : "margin-top:8px;")
+          + QUOTE_ISLAND_CONTAINMENT_STYLE;
+      };
+      updateQuoteStyle(node.attrs.showQuoteBorder !== false);
 
       // CRITICAL: render the quoted email inside a Shadow Root. The app's
       // global CSS (Tailwind preflight, .tiptap table/td rules, box-sizing
@@ -218,6 +227,7 @@ export const QuotedHtml = TiptapNode.create({
         },
         update: (updatedNode) => {
           if (updatedNode.type.name !== "quotedHtml") return false;
+          updateQuoteStyle(updatedNode.attrs.showQuoteBorder !== false);
           // Don't clobber the caret while the user is redacting inside.
           if (!focused && (updatedNode.attrs.html || "") !== renderedHtml) {
             render(updatedNode.attrs.html || "");
@@ -256,7 +266,7 @@ export function serializeEditorContent(editor: Editor): string {
       // Emit the SAME wrapper buildQuotedHtmlBlock produces, so a saved draft
       // round-trips: re-opening parses this back into a QuotedHtml node
       // instead of letting the schema mangle the raw table layout again.
-      parts.push(buildQuotedHtmlBlock((node.attrs.html as string) || ""));
+      parts.push(buildQuotedHtmlBlock((node.attrs.html as string) || "", { showQuoteBorder: node.attrs.showQuoteBorder !== false }));
       return;
     }
     if (node.type.name === "signatureBlock") {
@@ -286,8 +296,29 @@ export function serializeEditorContent(editor: Editor): string {
  */
 export function buildQuotedHtmlBlock(
   sanitizedInnerHtml: string,
-  opts: { remoteAllowed?: boolean } = {},
+  opts: { remoteAllowed?: boolean; showQuoteBorder?: boolean } = {},
 ): string {
+  const showQuoteBorder = opts.showQuoteBorder !== false;
+  let html = sanitizedInnerHtml;
+  if (!showQuoteBorder) {
+    // Outlook-style replies flatten quote levels, including earlier replies.
+    // Work on sanitized DOM so tables, links and signatures remain intact.
+    const container = document.createElement("div");
+    container.innerHTML = html;
+    container.querySelectorAll("blockquote").forEach((quote) => {
+      const block = document.createElement("div");
+      block.append(...Array.from(quote.childNodes));
+      quote.replaceWith(block);
+    });
+    container.querySelectorAll<HTMLElement>(`[${QUOTED_HTML_MARKER}]`).forEach((quote) => {
+      quote.setAttribute("data-quote-border", "false");
+      quote.style.borderLeft = "none";
+      quote.style.paddingLeft = "0";
+    });
+    html = container.innerHTML;
+  }
   const remote = opts.remoteAllowed ? ` ${QUOTED_REMOTE_ALLOWED_ATTR}="allowed"` : "";
-  return `<div ${QUOTED_HTML_MARKER}${remote} style="${QUOTE_BAR_STYLE}">${sanitizedInnerHtml}</div>`;
+  const borderAttribute = showQuoteBorder ? "" : ' data-quote-border="false"';
+  const style = showQuoteBorder ? QUOTE_BAR_STYLE : "margin-top:8px;";
+  return `<div ${QUOTED_HTML_MARKER}${remote}${borderAttribute} style="${style}">${html}</div>`;
 }
diff --git a/lib/plugin-types.ts b/lib/plugin-types.ts
index 4df1b48c9..2eb8212fe 100644
--- a/lib/plugin-types.ts
+++ b/lib/plugin-types.ts
@@ -1105,7 +1105,8 @@ export interface QuoteHeader {
   text: string;
   /**
    * When false, the composer skips its default blockquote wrapping around the
-   * quoted body (HTML mode only). Use this for the Outlook style where the
+   * quoted body, including HTML islands and nested blockquotes (HTML mode only).
+   * This preference persists when saving/reopening drafts. Use this for the Outlook style where the
    * quoted message is intended to follow the header without indentation.
    * Defaults to true (preserve the existing blockquote wrapping).
    */