diff --git a/components/email/email-composer.tsx b/components/email/email-composer.tsx
index fb10c866..ae937fc5 100644
--- a/components/email/email-composer.tsx
+++ b/components/email/email-composer.tsx
@@ -2143,6 +2143,7 @@ export function EmailComposer({
                 </div>
               ) : identities.length > 1 ? (
                 <select
+                  data-testid="composer-from"
                   value={selectedIdentityId || primaryIdentity?.id || ''}
                   onChange={(e) => setSelectedIdentityId(e.target.value)}
                   className="flex-1 bg-transparent text-sm text-foreground outline-none cursor-pointer hover:text-muted-foreground transition-colors min-w-0 truncate"
@@ -2174,7 +2175,7 @@ export function EmailComposer({
                       })}
                 </select>
               ) : (
-                <span className="text-sm text-foreground flex-1 truncate">
+                <span data-testid="composer-from" className="text-sm text-foreground flex-1 truncate">
                   {subAddressTag ? (
                     <span className="font-mono">
                       {generateSubAddress(primaryIdentity?.email || '', subAddressTag, subAddressDelimiter)}
diff --git a/integration/stalwart/entrypoint.sh b/integration/stalwart/entrypoint.sh
index ea45f91e..61cdc8fc 100755
--- a/integration/stalwart/entrypoint.sh
+++ b/integration/stalwart/entrypoint.sh
@@ -108,6 +108,31 @@ if [ ! -f "${MARKER}" ]; then
     "${STALWART_CLI}" apply --file "${PLAN_ACCOUNTS}" --quiet
   rm -f "${PLAN_ACCOUNTS}"
 
+  # Make 'carol' a member of the 'team' group *before her first login*, so she
+  # already has the shared group mailbox (its folders show under "Shared") and
+  # the team@ send-as identity. This provisions the issue #569 scenario: the
+  # composer's From dropdown should then offer the group address. Membership is
+  # a set keyed by the group's server-assigned account id (see the User schema's
+  # memberGroupIds), so the ids are resolved here, mirroring DOMAIN_ID above.
+  # carol (not alice/bob) is used so the single-/multi-account sync specs, which
+  # drive alice and bob, keep a clean unshared environment.
+  q_account_id() {
+    STALWART_URL=${LOCAL_URL} STALWART_USER=admin STALWART_PASSWORD=${ADMIN_PASS} \
+      "${STALWART_CLI}" query Account --json 2>/dev/null \
+      | grep "\"emailAddress\":\"$1\"" \
+      | sed -E 's/.*"id":"([^"]+)".*/\1/'
+  }
+  CAROL_ID=$(q_account_id "carol@example.org")
+  TEAM_ID=$(q_account_id "team@example.org")
+  if [ -n "${CAROL_ID}" ] && [ -n "${TEAM_ID}" ]; then
+    log "Adding carol (${CAROL_ID}) to the team group (${TEAM_ID}) [issue #569]"
+    STALWART_URL=${LOCAL_URL} STALWART_USER=admin STALWART_PASSWORD=${ADMIN_PASS} \
+      "${STALWART_CLI}" update Account "${CAROL_ID}" \
+        --field "memberGroupIds={\"${TEAM_ID}\":true}" >/dev/null
+  else
+    log "WARNING: could not resolve account ids (carol='${CAROL_ID}' team='${TEAM_ID}'); skipping group membership"
+  fi
+
   # Default inbound throttles (sender->recipient + sender-IP) otherwise trip
   # 452 4.4.5 when a test blasts many messages. Stalwart re-seeds the defaults
   # on every start when absent, so deleting is useless; disable them instead,
diff --git a/integration/stalwart/plan-accounts.ndjson.tpl b/integration/stalwart/plan-accounts.ndjson.tpl
index 43d6fa48..aaf58263 100644
--- a/integration/stalwart/plan-accounts.ndjson.tpl
+++ b/integration/stalwart/plan-accounts.ndjson.tpl
@@ -1,6 +1,7 @@
 {"@type":"create","object":"Account","value":{"alice":{"@type":"User","name":"alice","domainId":"${DOMAIN_ID}","description":"Integration test mailbox alice","credentials":{"0":{"@type":"Password","secret":"${TEST_ACCOUNT_PASSWORD}"}}}}}
 {"@type":"create","object":"Account","value":{"bob":{"@type":"User","name":"bob","domainId":"${DOMAIN_ID}","description":"Integration test mailbox bob","credentials":{"0":{"@type":"Password","secret":"${TEST_ACCOUNT_PASSWORD}"}}}}}
 {"@type":"create","object":"Account","value":{"carol":{"@type":"User","name":"carol","domainId":"${DOMAIN_ID}","description":"Integration test mailbox carol","credentials":{"0":{"@type":"Password","secret":"${TEST_ACCOUNT_PASSWORD}"}}}}}
+{"@type":"create","object":"Account","value":{"team":{"@type":"Group","name":"team","domainId":"${DOMAIN_ID}","description":"Team shared mailbox"}}}
 {"@type":"create","object":"NetworkListener","value":{"submission":{"name":"submission","protocol":"smtp","bind":{"[::]:587":true},"tlsImplicit":false,"useTls":false,"socketReuseAddress":true,"socketNoDelay":true}}}
 {"@type":"create","object":"NetworkListener","value":{"imap":{"name":"imap","protocol":"imap","bind":{"[::]:143":true},"tlsImplicit":false,"useTls":false,"socketReuseAddress":true,"socketNoDelay":true}}}
 {"@type":"update","object":"MtaStageAuth","value":{"saslMechanisms":{"match":{"0":{"if":"local_port != 25","then":"[plain, login, oauthbearer, xoauth2]"}},"else":"false"}}}
diff --git a/integration/tests/04-shared-identity.spec.ts b/integration/tests/04-shared-identity.spec.ts
new file mode 100644
index 00000000..a47a7250
--- /dev/null
+++ b/integration/tests/04-shared-identity.spec.ts
@@ -0,0 +1,59 @@
+import { test, expect } from '@playwright/test';
+import { ACCOUNTS, GROUP } from './helpers/config';
+import { JmapClient } from './helpers/jmap';
+import { login, forceSync, openComposer, composerFromOptions } from './helpers/app';
+
+/**
+ * Issue #569 — the composer's "From" dropdown should include identities from
+ * shared/group accounts, not only the logged-in (connected) accounts.
+ *
+ * Scenario under test (the one expected to already work): a Stalwart *group*
+ * mailbox `team@example.org` is provisioned and `carol` is made a member of it
+ * *before her first login* (integration/stalwart/plan-accounts.ndjson.tpl +
+ * entrypoint.sh). As a member she gets the group's shared folders (shown under
+ * "Shared") and — per Stalwart — a `team@` send-as identity (Stalwart returns
+ * it among the member's own account identities). The composer should therefore
+ * offer `team@example.org` as a sender alongside her own address.
+ */
+const member = ACCOUNTS[GROUP.team.memberOf];
+const { team } = GROUP;
+
+test.describe('Composer From: shared/group identities (issue #569)', () => {
+  test('the pre-provisioned group account is reachable in the member’s JMAP session', async () => {
+    // Server-side guard for the UI expectation below: if this fails, the
+    // bootstrap group provisioning is broken (not the app). The member must see
+    // the group account in her session, and it must expose a team@ identity she
+    // can send as.
+    const memberClient = await JmapClient.connect(member.email, member.password);
+    expect(memberClient.sharedAccountNames()).toContain(team.email);
+
+    const groupAccountId = Object.entries(memberClient.accounts).find(
+      ([, name]) => name === team.email,
+    )?.[0];
+    expect(groupAccountId).toBeTruthy();
+
+    const res = await memberClient.request([
+      ['Identity/get', { accountId: groupAccountId! }, '0'],
+    ]);
+    const groupIdentityEmails = (res.methodResponses[0][1].list as { email: string }[]).map(
+      (i) => i.email,
+    );
+    expect(groupIdentityEmails).toContain(team.email);
+  });
+
+  test('the composer From selector offers the group address', async ({ page }) => {
+    await login(page, member);
+    // Shared accounts/identities are discovered from the JMAP session; give the
+    // client a beat to settle them after the first render.
+    await forceSync(page);
+
+    await openComposer(page);
+
+    // The group address alice can send as should be one of the From choices.
+    // If #569 is unaddressed the control collapses to her own address only and
+    // this poll times out — which is the point: it pins the expected behaviour.
+    await expect
+      .poll(async () => (await composerFromOptions(page)).join(' | '), { timeout: 15000 })
+      .toContain(team.email);
+  });
+});
diff --git a/integration/tests/helpers/app.ts b/integration/tests/helpers/app.ts
index 2d859c18..7922d4ab 100644
--- a/integration/tests/helpers/app.ts
+++ b/integration/tests/helpers/app.ts
@@ -169,6 +169,31 @@ export async function openFolder(page: Page, sel: FolderSelector): Promise<void>
   await folderRow(page, sel).first().click();
 }
 
+/** Open the "New message" composer and wait for it to render. */
+export async function openComposer(page: Page): Promise<Locator> {
+  await page.locator('[data-tour="compose-button"]').first().click();
+  const composer = page.locator('[data-testid="email-composer"]');
+  await composer.waitFor({ state: 'visible', timeout: 15000 });
+  return composer;
+}
+
+/**
+ * The sender addresses the composer's From control offers.
+ *
+ * With more than one identity the control is a <select> and each choice is an
+ * <option>; with a single identity it collapses to a static <span> that shows
+ * only that address. Returning the raw text of whichever is rendered lets a
+ * test assert on the *set of senders* without caring which shape it took.
+ */
+export async function composerFromOptions(page: Page): Promise<string[]> {
+  const from = page.locator('[data-testid="composer-from"]').first();
+  await from.waitFor({ state: 'visible', timeout: 10000 });
+  if ((await from.locator('option').count()) > 0) {
+    return from.locator('option').allTextContents();
+  }
+  return [await from.innerText()];
+}
+
 /** Locator for an email row by (exact) subject. */
 export function emailItem(page: Page, subject: string): Locator {
   return page.locator(`[data-testid="email-list-item"][data-subject="${subject}"]`);
diff --git a/integration/tests/helpers/config.ts b/integration/tests/helpers/config.ts
index cf87436e..b97998b4 100644
--- a/integration/tests/helpers/config.ts
+++ b/integration/tests/helpers/config.ts
@@ -43,3 +43,14 @@ export const ACCOUNTS = {
 } as const;
 
 export type AccountKey = keyof typeof ACCOUNTS;
+
+/**
+ * The shared *group* account provisioned by the bootstrap (a Stalwart Group
+ * principal, not a login). `carol` is made a member before her first login, so
+ * she sees the group's folders under "Shared" and can send as its address.
+ * Groups have no password of their own — access is via a member's session.
+ * (carol, rather than alice/bob, keeps the sync specs' accounts unshared.)
+ */
+export const GROUP = {
+  team: { user: 'team', email: `team@${DOMAIN}`, memberOf: 'carol' as AccountKey },
+} as const;
diff --git a/integration/tests/helpers/jmap.ts b/integration/tests/helpers/jmap.ts
index e7a1dbe8..372ef719 100644
--- a/integration/tests/helpers/jmap.ts
+++ b/integration/tests/helpers/jmap.ts
@@ -12,6 +12,8 @@ import { JMAP_URL } from './config';
 
 const CORE = 'urn:ietf:params:jmap:core';
 const MAIL = 'urn:ietf:params:jmap:mail';
+// Identity/* lives under the submission capability, not mail.
+const SUBMISSION = 'urn:ietf:params:jmap:submission';
 
 interface JmapMailbox {
   id: string;
@@ -28,6 +30,9 @@ export class JmapClient {
   private authHeader: string;
   private apiUrl: string;
   accountId = '';
+  /** Every account visible in this user's session (own + shared/group),
+   *  keyed by accountId -> account name (its email address). */
+  accounts: Record<string, string> = {};
 
   private constructor(private email: string, password: string) {
     this.authHeader = 'Basic ' + Buffer.from(`${email}:${password}`).toString('base64');
@@ -46,14 +51,25 @@ export class JmapClient {
     const primary = session.primaryAccounts?.[MAIL];
     if (!primary) throw new Error(`No mail account for ${email} in JMAP session`);
     c.accountId = primary;
+    c.accounts = Object.fromEntries(
+      Object.entries(session.accounts ?? {}).map(([id, a]) => [id, (a as { name: string }).name]),
+    );
     return c;
   }
 
+  /** Names (email addresses) of the shared/group accounts this user can access,
+   *  i.e. everything in the session except the user's own primary account. */
+  sharedAccountNames(): string[] {
+    return Object.entries(this.accounts)
+      .filter(([id]) => id !== this.accountId)
+      .map(([, name]) => name);
+  }
+
   async request(methodCalls: MethodCall[]): Promise<any> {
     const res = await fetch(this.apiUrl, {
       method: 'POST',
       headers: { Authorization: this.authHeader, 'Content-Type': 'application/json' },
-      body: JSON.stringify({ using: [CORE, MAIL], methodCalls }),
+      body: JSON.stringify({ using: [CORE, MAIL, SUBMISSION], methodCalls }),
     });
     if (!res.ok) throw new Error(`JMAP request failed: ${res.status} ${await res.text()}`);
     return res.json();