diff --git a/apps/api/src/modules/mail/__tests__/fakes.ts b/apps/api/src/modules/mail/__tests__/fakes.ts
new file mode 100644
index 0000000..d67a019
--- /dev/null
+++ b/apps/api/src/modules/mail/__tests__/fakes.ts
@@ -0,0 +1,337 @@
+/**
+ * 测试夹具 —— 内存 store(用例测试用)、假 provider(邮件通道是外界,替身允许)、EML 构造。
+ * 系统内部机制在 IT 里真跑(mail-store.it.test.ts);这里的内存 store 只服务用例逻辑。
+ */
+import type { MailAccountKind, MailProbeReport } from '@contracts';
+import { isDue } from '../internal/domain/due.ts';
+import { imapCursor, wecomCursor } from '../internal/domain/cursor.ts';
+import type {
+  AttachmentStore,
+  Clock,
+  DeliveryRecord,
+  IdGenerator,
+  InboundRecord,
+  InboundStore,
+  MailAccountRecord,
+  MailAccountStore,
+  MailCursor,
+  MailProvider,
+  OutboundMessage,
+  OutboundRecord,
+  OutboundStore,
+  RawMessage,
+  SecretBox,
+} from '../port.ts';
+
+const CRLF = '\r\n';
+
+export function fixedClock(iso = '2026-08-25T10:00:00Z'): Clock & { tick(ms: number): void } {
+  let t = new Date(iso).getTime();
+  return {
+    now: () => new Date(t),
+    tick(ms) {
+      t += ms;
+    },
+  };
+}
+
+export function seqIds(prefix = 'id'): IdGenerator {
+  let n = 0;
+  return {
+    next: () => {
+      n += 1;
+      return `${prefix}-${n}`;
+    },
+  };
+}
+
+export const plainSecrets: SecretBox = {
+  seal: (s) => `sealed:${s}`,
+  open: (c) => {
+    if (!c.startsWith('sealed:')) throw new Error('密文格式非法');
+    return c.slice('sealed:'.length);
+  },
+};
+
+export function account(over: Partial<MailAccountRecord> = {}): MailAccountRecord {
+  const now = new Date('2026-08-25T09:00:00Z');
+  return {
+    id: 'acc-1',
+    kind: 'imap-smtp',
+    name: '销售信箱',
+    address: 'sales@we.com',
+    displayName: '销售部',
+    enabled: true,
+    isDefault: true,
+    pollIntervalSec: 30,
+    channelId: 'ch-1',
+    backfillFrom: null,
+    settings: { folder: 'INBOX' },
+    secretCipher: `sealed:${JSON.stringify({ password: 'pw-1234' })}`,
+    cursor: null,
+    lastPolledAt: null,
+    lastPollError: null,
+    lastInboundAt: null,
+    pollingUntil: null,
+    createdAt: now,
+    updatedAt: now,
+    ...over,
+  };
+}
+
+export function memoryAccounts(clock: Clock): MailAccountStore & { rows: Map<string, MailAccountRecord> } {
+  const rows = new Map<string, MailAccountRecord>();
+  return {
+    rows,
+    async list() {
+      return [...rows.values()].sort((a, b) => a.name.localeCompare(b.name));
+    },
+    async get(id) {
+      return rows.get(id);
+    },
+    async findByName(name) {
+      return [...rows.values()].find((r) => r.name === name);
+    },
+    async save(record) {
+      if (record.isDefault) {
+        for (const [k, v] of rows) if (k !== record.id && v.isDefault) rows.set(k, { ...v, isDefault: false });
+      }
+      rows.set(record.id, record);
+    },
+    async remove(id) {
+      rows.delete(id);
+    },
+    async listDue(now) {
+      return [...rows.values()].filter((r) => isDue(r, now));
+    },
+    async claimPolling(id, leaseMs) {
+      const r = rows.get(id);
+      const now = clock.now();
+      if (r === undefined || !r.enabled) return false;
+      if (r.pollingUntil !== null && r.pollingUntil.getTime() > now.getTime()) return false;
+      rows.set(id, { ...r, pollingUntil: new Date(now.getTime() + leaseMs) });
+      return true;
+    },
+    async releasePolling(id) {
+      const r = rows.get(id);
+      if (r !== undefined) rows.set(id, { ...r, pollingUntil: null });
+    },
+    async savePoll(id, patch) {
+      const r = rows.get(id);
+      if (r === undefined) return;
+      rows.set(id, {
+        ...r,
+        ...(patch.cursor === undefined ? {} : { cursor: patch.cursor }),
+        ...(patch.polledAt === undefined ? {} : { lastPolledAt: patch.polledAt }),
+        ...(patch.error === undefined ? {} : { lastPollError: patch.error }),
+        ...(patch.lastInboundAt === undefined ? {} : { lastInboundAt: patch.lastInboundAt }),
+        ...(patch.address === undefined ? {} : { address: patch.address }),
+      });
+    },
+  };
+}
+
+export function memoryInbound(): InboundStore & { rows: Map<string, InboundRecord>; deliveries: Map<string, DeliveryRecord> } {
+  const rows = new Map<string, InboundRecord>();
+  const deliveries = new Map<string, DeliveryRecord>();
+  // 与 DB store 同序:按订阅方名排(测试里对顺序有断言)
+  const of = (mailId: string): DeliveryRecord[] =>
+    [...deliveries.values()].filter((d) => d.mailId === mailId).sort((a, b) => a.subscriber.localeCompare(b.subscriber));
+  return {
+    rows,
+    deliveries,
+    async insert(record) {
+      for (const r of rows.values()) {
+        if (r.accountId === record.accountId && (r.messageId === record.messageId || r.providerRef === record.providerRef)) {
+          return { inserted: false };
+        }
+      }
+      rows.set(record.id, record);
+      return { inserted: true };
+    },
+    async knownProviderRefs(accountId, refs) {
+      return new Set([...rows.values()].filter((r) => r.accountId === accountId && refs.includes(r.providerRef)).map((r) => r.providerRef));
+    },
+    async list(query) {
+      return [...rows.values()]
+        .filter((r) => query.accountId === undefined || r.accountId === query.accountId)
+        .sort((a, b) => b.receivedAt.getTime() - a.receivedAt.getTime())
+        .slice(0, query.limit)
+        .map((record) => ({ record, deliveries: of(record.id) }));
+    },
+    async get(mailId) {
+      const record = rows.get(mailId);
+      return record === undefined ? undefined : { record, deliveries: of(mailId) };
+    },
+    async setDelivery(delivery) {
+      deliveries.set(`${delivery.mailId}|${delivery.subscriber}`, delivery);
+    },
+  };
+}
+
+export function memoryOutbound(): OutboundStore & { rows: Map<string, OutboundRecord> } {
+  const rows = new Map<string, OutboundRecord>();
+  return {
+    rows,
+    async insert(record) {
+      if (record.idempotencyKey !== null && [...rows.values()].some((r) => r.idempotencyKey === record.idempotencyKey)) {
+        throw new Error('duplicate key value violates unique constraint "mail_outbound_idem_key"');
+      }
+      rows.set(record.id, record);
+    },
+    async byIdempotencyKey(key) {
+      return [...rows.values()].find((r) => r.idempotencyKey === key);
+    },
+    async setState(id, state, patch) {
+      const r = rows.get(id);
+      if (r === undefined) return;
+      rows.set(id, {
+        ...r,
+        state,
+        ...(patch.error === undefined ? {} : { error: patch.error }),
+        ...(patch.providerRef === undefined ? {} : { providerRef: patch.providerRef }),
+        ...(patch.sentAt === undefined ? {} : { sentAt: patch.sentAt }),
+      });
+    },
+    async list(query) {
+      return [...rows.values()]
+        .filter((r) => query.accountId === undefined || r.accountId === query.accountId)
+        .sort((a, b) => b.createdAt.getTime() - a.createdAt.getTime())
+        .slice(0, query.limit);
+    },
+  };
+}
+
+export function memoryAttachments(): AttachmentStore & { files: Map<string, { name: string; contentType: string; bytes: Uint8Array; note: string }> } {
+  const files = new Map<string, { name: string; contentType: string; bytes: Uint8Array; note: string }>();
+  let n = 0;
+  return {
+    files,
+    async put(file) {
+      n += 1;
+      const ref = `up-${n}`;
+      files.set(ref, { ...file });
+      return { ref };
+    },
+    async get(ref) {
+      const f = files.get(ref);
+      return f === undefined ? undefined : { name: f.name, contentType: f.contentType, bytes: f.bytes };
+    },
+  };
+}
+
+export type FakeProvider = MailProvider & {
+  readonly sent: OutboundMessage[];
+  readonly pullCalls: Array<{ cursor: MailCursor; limit: number }>;
+  queue(...messages: RawMessage[]): void;
+  failPullWith(error: Error | undefined): void;
+  failSendWith(error: Error | undefined): void;
+  probeWith(report: MailProbeReport | undefined): void;
+};
+
+/** 可脚本化的假 provider:排队的信按 limit 交出去,IMAP 形逐封带 cursorAfter */
+export function fakeProvider(kind: MailAccountKind = 'imap-smtp'): FakeProvider {
+  const pending: RawMessage[] = [];
+  const sent: OutboundMessage[] = [];
+  const pullCalls: Array<{ cursor: MailCursor; limit: number }> = [];
+  let pullError: Error | undefined;
+  let sendError: Error | undefined;
+  let probeReport: MailProbeReport | undefined;
+  let uidSeq = 0;
+  return {
+    kind,
+    sent,
+    pullCalls,
+    queue(...messages) {
+      pending.push(...messages);
+    },
+    failPullWith(error) {
+      pullError = error;
+    },
+    failSendWith(error) {
+      sendError = error;
+    },
+    probeWith(report) {
+      probeReport = report;
+    },
+    async probe(accountArg) {
+      return (
+        probeReport ?? {
+          kind,
+          address: accountArg.address,
+          receive: { ok: true, latencyMs: 1 },
+          send: kind === 'wecom' ? { checked: false, note: '发信权限只能在真发时验证' } : { checked: true, ok: true },
+        }
+      );
+    },
+    async anchor(_accountArg, _backfillFrom, now) {
+      return kind === 'imap-smtp' ? imapCursor('v1', 0) : wecomCursor(Math.floor(now.getTime() / 1000));
+    },
+    async pull(_accountArg, cursor, opts) {
+      pullCalls.push({ cursor, limit: opts.limit });
+      if (pullError !== undefined) throw pullError;
+      const batch = pending.splice(0, opts.limit).map((m) => {
+        if (kind !== 'imap-smtp' || m.cursorAfter !== undefined) return m;
+        uidSeq += 1;
+        return { ...m, cursorAfter: imapCursor('v1', uidSeq) };
+      });
+      const last = batch.at(-1)?.cursorAfter;
+      const next = kind === 'imap-smtp' ? (last ?? cursor) : wecomCursor(Math.floor(opts.now.getTime() / 1000));
+      return { messages: batch, cursor: next, more: pending.length > 0 };
+    },
+    async send(_accountArg, message) {
+      if (sendError !== undefined) throw sendError;
+      sent.push(message);
+      return { providerRef: `fake:${sent.length}` };
+    },
+  };
+}
+
+export function rawMessage(providerRef: string, eml: Uint8Array, receivedAt = new Date('2026-08-25T09:30:00Z')): RawMessage {
+  return { providerRef, eml, receivedAt };
+}
+
+/** 极简 RFC822 构造:够 postal-mime 解出地址、主题、正文、附件 */
+export function eml(parts: {
+  from?: string;
+  to?: string;
+  cc?: string;
+  subject?: string;
+  text?: string;
+  html?: string;
+  messageId?: string;
+  inReplyTo?: string;
+  references?: string;
+  date?: string;
+  attachment?: { name: string; contentType: string; content: string };
+}): Uint8Array {
+  const headers = [
+    `From: ${parts.from ?? 'buyer@acme.com'}`,
+    `To: ${parts.to ?? 'sales@we.com'}`,
+    ...(parts.cc === undefined ? [] : [`Cc: ${parts.cc}`]),
+    `Subject: ${parts.subject ?? '询价'}`,
+    ...(parts.messageId === undefined ? [] : [`Message-ID: ${parts.messageId}`]),
+    ...(parts.inReplyTo === undefined ? [] : [`In-Reply-To: ${parts.inReplyTo}`]),
+    ...(parts.references === undefined ? [] : [`References: ${parts.references}`]),
+    `Date: ${parts.date ?? 'Tue, 25 Aug 2026 09:00:00 +0800'}`,
+    'MIME-Version: 1.0',
+  ];
+  const text = parts.text ?? '你好,请报价';
+  if (parts.html === undefined && parts.attachment === undefined) {
+    return new TextEncoder().encode([...headers, 'Content-Type: text/plain; charset=utf-8', '', text, ''].join(CRLF));
+  }
+  const lines = [...headers, 'Content-Type: multipart/mixed; boundary="B1"', '', '--B1', 'Content-Type: text/plain; charset=utf-8', '', text];
+  if (parts.html !== undefined) lines.push('--B1', 'Content-Type: text/html; charset=utf-8', '', parts.html);
+  if (parts.attachment !== undefined) {
+    lines.push(
+      '--B1',
+      `Content-Type: ${parts.attachment.contentType}; name="${parts.attachment.name}"`,
+      `Content-Disposition: attachment; filename="${parts.attachment.name}"`,
+      'Content-Transfer-Encoding: base64',
+      '',
+      Buffer.from(parts.attachment.content, 'utf8').toString('base64'),
+    );
+  }
+  lines.push('--B1--', '');
+  return new TextEncoder().encode(lines.join(CRLF));
+}
diff --git a/apps/api/src/modules/mail/__tests__/postal-mime-parser.test.ts b/apps/api/src/modules/mail/__tests__/postal-mime-parser.test.ts
new file mode 100644
index 0000000..0047ea2
--- /dev/null
+++ b/apps/api/src/modules/mail/__tests__/postal-mime-parser.test.ts
@@ -0,0 +1,81 @@
+/** MIME 解析 —— 真 postal-mime:GBK 编码字头、群组地址、References 拆串、纯 html、附件字节 */
+import { describe, expect, it } from 'vitest';
+import { createPostalMimeParser } from '../internal/adapter/postal-mime-parser.ts';
+import { eml } from './fakes.ts';
+
+const parser = createPostalMimeParser();
+const CRLF = '\r\n';
+
+describe('createPostalMimeParser', () => {
+  it('地址 / 主题 / 正文 / Message-ID / In-Reply-To / References / 日期', async () => {
+    const parsed = await parser.parse(
+      eml({
+        from: '"张三" <buyer@acme.com>',
+        to: 'sales@we.com, "Ops" <ops@we.com>',
+        subject: '询价 RFQ-1',
+        messageId: '<m1@acme.com>',
+        inReplyTo: '<q1@we.com>',
+        references: '<root@we.com> <q1@we.com>',
+        text: '你好,请报价',
+      }),
+    );
+    expect(parsed.from).toEqual({ address: 'buyer@acme.com', name: '张三' });
+    expect(parsed.to).toEqual([
+      { address: 'sales@we.com', name: '' },
+      { address: 'ops@we.com', name: 'Ops' },
+    ]);
+    expect(parsed.subject).toBe('询价 RFQ-1');
+    expect(parsed.messageId).toBe('<m1@acme.com>');
+    expect(parsed.inReplyTo).toBe('<q1@we.com>');
+    expect(parsed.references).toEqual(['<root@we.com>', '<q1@we.com>']);
+    expect(parsed.text?.trim()).toBe('你好,请报价');
+    expect(parsed.date?.toISOString()).toBe('2026-08-25T01:00:00.000Z');
+  });
+
+  it('GBK 的 =?GBK?B?…?= 主题与 charset=gbk 正文解成中文(Node 自带 TextDecoder)', async () => {
+    const subject = Buffer.from([0xd1, 0xaf, 0xbc, 0xdb]).toString('base64'); // 询价
+    const body = Buffer.from([0xc4, 0xe3, 0xba, 0xc3]).toString('base64'); // 你好
+    const raw = [
+      'From: buyer@acme.com',
+      'To: sales@we.com',
+      `Subject: =?GBK?B?${subject}?=`,
+      'Content-Type: text/plain; charset=gbk',
+      'Content-Transfer-Encoding: base64',
+      '',
+      body,
+      '',
+    ].join(CRLF);
+    const parsed = await parser.parse(new TextEncoder().encode(raw));
+    expect(parsed.subject).toBe('询价');
+    expect(parsed.text?.trim()).toBe('你好');
+  });
+
+  it('群组地址摊平;没有 Cc 就是空数组', async () => {
+    const raw = ['From: a@x.com', 'To: team: b@x.com, "C" <c@x.com>;', 'Subject: s', '', 'body', ''].join(CRLF);
+    const parsed = await parser.parse(new TextEncoder().encode(raw));
+    expect(parsed.to).toEqual([
+      { address: 'b@x.com', name: '' },
+      { address: 'c@x.com', name: 'C' },
+    ]);
+    expect(parsed.cc).toEqual([]);
+  });
+
+  it('纯 html 的信 text 缺席、html 在;没有 Message-ID / From 也不抛', async () => {
+    const raw = ['Subject: x', 'Content-Type: text/html', '', '<b>only html</b>', ''].join(CRLF);
+    const parsed = await parser.parse(new TextEncoder().encode(raw));
+    expect(parsed.text).toBeUndefined();
+    expect(parsed.html).toContain('only html');
+    expect(parsed.messageId).toBeUndefined();
+    expect(parsed.from).toBeUndefined();
+    expect(parsed.date).toBeUndefined();
+  });
+
+  it('附件:文件名、类型、字节(ArrayBuffer → Uint8Array)', async () => {
+    const parsed = await parser.parse(eml({ attachment: { name: 'bom.xlsx', contentType: 'application/vnd.ms-excel', content: 'PKxyz' } }));
+    expect(parsed.attachments).toHaveLength(1);
+    expect(parsed.attachments[0]?.name).toBe('bom.xlsx');
+    expect(parsed.attachments[0]?.contentType).toBe('application/vnd.ms-excel');
+    expect(parsed.attachments[0]?.bytes).toBeInstanceOf(Uint8Array);
+    expect(new TextDecoder().decode(parsed.attachments[0]?.bytes)).toBe('PKxyz');
+  });
+});
diff --git a/apps/api/src/modules/mail/index.ts b/apps/api/src/modules/mail/index.ts
index 05e1669..79fadcf 100644
--- a/apps/api/src/modules/mail/index.ts
+++ b/apps/api/src/modules/mail/index.ts
@@ -80,3 +80,4 @@ export { cursorReset, mergeAccount, secretOf, viewOf } from './internal/domain/a
 
 export { createInboundStore, createMailAccountStore, createOutboundStore } from './internal/adapter/mail-store.ts';
 export { mailAccountTable, mailInboundDeliveryTable, mailInboundTable, mailOutboundTable } from './internal/adapter/mail-schema.ts';
+export { createPostalMimeParser } from './internal/adapter/postal-mime-parser.ts';
diff --git a/apps/api/src/modules/mail/internal/adapter/postal-mime-parser.ts b/apps/api/src/modules/mail/internal/adapter/postal-mime-parser.ts
new file mode 100644
index 0000000..46d13f0
--- /dev/null
+++ b/apps/api/src/modules/mail/internal/adapter/postal-mime-parser.ts
@@ -0,0 +1,63 @@
+/**
+ * MIME 解析 —— postal-mime(零依赖;GBK / GB18030 走 Node 自带 TextDecoder)。
+ * 两条接入路共用:IMAP 拉到的 source 与 wecom `read_mail` 的 EML 都从这里过。
+ */
+import PostalMime from 'postal-mime';
+import type { Address } from 'postal-mime';
+import type { MailAddress } from '@contracts';
+import type { MimeParser, ParsedMail } from '../../port.ts';
+
+function mailboxesOf(list: readonly Address[] | undefined): MailAddress[] {
+  const out: MailAddress[] = [];
+  for (const entry of list ?? []) {
+    if (entry.group !== undefined) {
+      for (const member of entry.group) out.push({ address: member.address, name: member.name });
+    } else if (entry.address !== undefined) {
+      out.push({ address: entry.address, name: entry.name });
+    }
+  }
+  return out;
+}
+
+/** References / In-Reply-To 是空白分隔的一串 <id>;拆开、去空 */
+function idsOf(value: string | undefined): string[] {
+  if (value === undefined) return [];
+  return value
+    .split(/\s+/)
+    .map((s) => s.trim())
+    .filter((s) => s !== '');
+}
+
+function bytesOf(content: ArrayBuffer | Uint8Array | string): Uint8Array {
+  if (typeof content === 'string') return new TextEncoder().encode(content);
+  return content instanceof Uint8Array ? content : new Uint8Array(content);
+}
+
+export function createPostalMimeParser(): MimeParser {
+  return {
+    async parse(eml): Promise<ParsedMail> {
+      const email = await PostalMime.parse(eml, { attachmentEncoding: 'arraybuffer' });
+      const from =
+        email.from !== undefined && email.from.address !== undefined ? { address: email.from.address, name: email.from.name } : undefined;
+      const date = email.date === undefined ? undefined : new Date(email.date);
+      const inReplyTo = idsOf(email.inReplyTo)[0];
+      return {
+        ...(email.messageId === undefined ? {} : { messageId: email.messageId }),
+        ...(inReplyTo === undefined ? {} : { inReplyTo }),
+        references: idsOf(email.references),
+        ...(from === undefined ? {} : { from }),
+        to: mailboxesOf(email.to),
+        cc: mailboxesOf(email.cc),
+        subject: email.subject ?? '',
+        ...(email.text === undefined ? {} : { text: email.text }),
+        ...(email.html === undefined ? {} : { html: email.html }),
+        ...(date === undefined || Number.isNaN(date.getTime()) ? {} : { date }),
+        attachments: email.attachments.map((a) => ({
+          name: a.filename ?? '',
+          contentType: a.mimeType,
+          bytes: bytesOf(a.content),
+        })),
+      };
+    },
+  };
+}