diff --git a/src/controllers/company.controller.js b/src/controllers/company.controller.js
index e3a6e48..070501a 100644
--- a/src/controllers/company.controller.js
+++ b/src/controllers/company.controller.js
@@ -1,6 +1,7 @@
 import * as companyService from '../services/company.service.js';
 import * as noteService from '../services/note.service.js';
 import * as companyReminderService from '../services/company-reminder.service.js';
+import * as companyEmailService from '../services/company-email.service.js';
 import { formatErrorResponse } from '../utils/errors.js';
 
 /**
@@ -44,6 +45,30 @@ export const getCompanyById = async (req, res) => {
   }
 };
 
+/**
+ * Get company email threads aggregated across user's email accounts
+ * GET /api/companies/:companyId/email-threads
+ */
+export const getCompanyEmailThreads = async (req, res) => {
+  try {
+    const userId = req.userId;
+    const { companyId } = req.params;
+
+    // Ensure company exists
+    await companyService.getCompanyById(companyId);
+
+    const result = await companyEmailService.getCompanyEmailThreads(companyId, userId);
+
+    res.status(200).json({
+      success: true,
+      data: result,
+    });
+  } catch (error) {
+    const errorResponse = formatErrorResponse(error, process.env.NODE_ENV === 'development');
+    res.status(error.statusCode || 500).json(errorResponse);
+  }
+};
+
 /**
  * Get company with relations (projects, todos, notes)
  * GET /api/companies/:companyId/details
diff --git a/src/db/migrations/0008_add_company_id_to_emails.sql b/src/db/migrations/0008_add_company_id_to_emails.sql
new file mode 100644
index 0000000..dc3a957
--- /dev/null
+++ b/src/db/migrations/0008_add_company_id_to_emails.sql
@@ -0,0 +1,20 @@
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_name = 'emails' AND column_name = 'company_id'
+    ) THEN
+        ALTER TABLE emails
+        ADD COLUMN company_id UUID REFERENCES companies(id) ON DELETE SET NULL;
+    END IF;
+END $$;
+
+CREATE INDEX IF NOT EXISTS idx_emails_company_id ON emails(company_id);
+CREATE INDEX IF NOT EXISTS idx_emails_company_thread ON emails(company_id, thread_id);
+
+UPDATE emails e
+SET company_id = c.company_id
+FROM contacts c
+WHERE e.contact_id = c.id
+  AND c.company_id IS NOT NULL
+  AND (e.company_id IS NULL OR e.company_id <> c.company_id);
diff --git a/src/db/schema.js b/src/db/schema.js
index b6ca7c5..6e91bba 100644
--- a/src/db/schema.js
+++ b/src/db/schema.js
@@ -85,6 +85,7 @@ export const emails = pgTable('emails', {
   id: uuid('id').primaryKey().defaultRandom(),
   emailAccountId: uuid('email_account_id').references(() => emailAccounts.id, { onDelete: 'cascade' }).notNull(),
   contactId: uuid('contact_id').references(() => contacts.id, { onDelete: 'cascade' }),
+  companyId: uuid('company_id').references(() => companies.id, { onDelete: 'set null' }),
   jmapId: text('jmap_id').unique(),
   messageId: text('message_id').unique(),
   threadId: text('thread_id'),
diff --git a/src/routes/company.routes.js b/src/routes/company.routes.js
index c999d4e..aa60e6c 100644
--- a/src/routes/company.routes.js
+++ b/src/routes/company.routes.js
@@ -14,6 +14,13 @@ router.use(authenticate);
 router.get('/reminders/summary', companyController.getReminderSummary);
 router.get('/reminders/counts', companyController.getReminderCountsByCompany);
 
+// Company email threads
+router.get(
+  '/:companyId/email-threads',
+  validateParams(z.object({ companyId: z.string().uuid() })),
+  companyController.getCompanyEmailThreads
+);
+
 /**
  * Company management
  */
diff --git a/src/routes/contact.routes.js b/src/routes/contact.routes.js
index 2f04422..6e1eaac 100644
--- a/src/routes/contact.routes.js
+++ b/src/routes/contact.routes.js
@@ -46,6 +46,40 @@ router.patch(
   contactController.updateContact
 );
 
+// Link company to contact
+router.post(
+  '/:contactId/link-company',
+  validateParams(z.object({ contactId: z.string().uuid() })),
+  validateBody(z.object({ companyId: z.string().uuid() })),
+  contactController.linkCompanyToContact
+);
+
+// Unlink company from contact
+router.post(
+  '/:contactId/unlink-company',
+  validateParams(z.object({ contactId: z.string().uuid() })),
+  contactController.unlinkCompanyFromContact
+);
+
+// Create company from contact
+router.post(
+  '/:contactId/create-company',
+  validateParams(z.object({ contactId: z.string().uuid() })),
+  validateBody(
+    z.object({
+      name: z.string().optional(),
+      email: z.string().email().optional(),
+      phone: z.string().optional(),
+      address: z.string().optional(),
+      city: z.string().optional(),
+      country: z.string().optional(),
+      website: z.string().optional(),
+      description: z.string().optional(),
+    })
+  ),
+  contactController.createCompanyFromContact
+);
+
 // Remove a contact
 router.delete(
   '/:contactId',
diff --git a/src/services/company-email.service.js b/src/services/company-email.service.js
new file mode 100644
index 0000000..eaebfa2
--- /dev/null
+++ b/src/services/company-email.service.js
@@ -0,0 +1,100 @@
+import { and, desc, eq, inArray } from 'drizzle-orm';
+import { db } from '../config/database.js';
+import { contacts, emailAccounts, emails, userEmailAccounts } from '../db/schema.js';
+
+export const getCompanyEmailThreads = async (companyId, userId) => {
+  const accountLinks = await db
+    .select({
+      id: emailAccounts.id,
+      email: emailAccounts.email,
+      isActive: emailAccounts.isActive,
+    })
+    .from(userEmailAccounts)
+    .innerJoin(emailAccounts, eq(userEmailAccounts.emailAccountId, emailAccounts.id))
+    .where(
+      and(
+        eq(userEmailAccounts.userId, userId),
+        eq(emailAccounts.isActive, true)
+      )
+    );
+
+  const accountIds = accountLinks.map((acc) => acc.id);
+
+  if (accountIds.length === 0) {
+    return { accounts: [], threads: [] };
+  }
+
+  const rows = await db
+    .select({
+      threadId: emails.threadId,
+      emailAccountId: emails.emailAccountId,
+      accountEmail: emailAccounts.email,
+      subject: emails.subject,
+      date: emails.date,
+      isRead: emails.isRead,
+      from: emails.from,
+      to: emails.to,
+      contactId: contacts.id,
+      contactEmail: contacts.email,
+      contactName: contacts.name,
+    })
+    .from(emails)
+    .innerJoin(emailAccounts, eq(emails.emailAccountId, emailAccounts.id))
+    .leftJoin(contacts, eq(emails.contactId, contacts.id))
+    .where(
+      and(
+        inArray(emails.emailAccountId, accountIds),
+        eq(emails.companyId, companyId)
+      )
+    )
+    .orderBy(desc(emails.date));
+
+  const threadsMap = new Map();
+
+  for (const row of rows) {
+    const threadKey = `${row.emailAccountId}:${row.threadId}`;
+    const lastDate = row.date ? new Date(row.date) : null;
+    const existing = threadsMap.get(threadKey);
+
+    if (!existing) {
+      threadsMap.set(threadKey, {
+        threadId: row.threadId,
+        emailAccountId: row.emailAccountId,
+        accountEmail: row.accountEmail,
+        contactId: row.contactId,
+        contactEmail: row.contactEmail,
+        contactName: row.contactName,
+        subject: row.subject,
+        lastFrom: row.from,
+        lastTo: row.to,
+        lastMessageAt: lastDate,
+        unreadCount: row.isRead ? 0 : 1,
+        totalCount: 1,
+      });
+      continue;
+    }
+
+    existing.totalCount += 1;
+    if (!row.isRead) {
+      existing.unreadCount += 1;
+    }
+
+    if (lastDate && (!existing.lastMessageAt || lastDate > existing.lastMessageAt)) {
+      existing.lastMessageAt = lastDate;
+      existing.subject = row.subject;
+      existing.lastFrom = row.from;
+      existing.lastTo = row.to;
+    }
+  }
+
+  const threads = Array.from(threadsMap.values()).sort((a, b) => {
+    const aTime = a.lastMessageAt ? a.lastMessageAt.getTime() : 0;
+    const bTime = b.lastMessageAt ? b.lastMessageAt.getTime() : 0;
+    return bTime - aTime;
+  });
+
+  return {
+    accounts: accountLinks,
+    threads,
+  };
+};
diff --git a/src/services/contact.service.js b/src/services/contact.service.js
index 27d1efe..de52f5e 100644
--- a/src/services/contact.service.js
+++ b/src/services/contact.service.js
@@ -88,7 +88,10 @@ export const addContact = async (emailAccountId, jmapConfig, email, name = '', n
       for (const emailToReassign of emailsToReassign) {
         await db
           .update(emails)
-          .set({ contactId: newContact.id })
+          .set({
+            contactId: newContact.id,
+            companyId: newContact.companyId || null,
+          })
           .where(eq(emails.id, emailToReassign.id));
       }
 
@@ -172,6 +175,15 @@ export const linkCompanyToContact = async (contactId, emailAccountId, companyId)
     .where(eq(contacts.id, contactId))
     .returning();
 
+  // Propagate company assignment to existing emails for this contact
+  await db
+    .update(emails)
+    .set({
+      companyId,
+      updatedAt: new Date(),
+    })
+    .where(eq(emails.contactId, contactId));
+
   return updated;
 };
 
@@ -190,6 +202,15 @@ export const unlinkCompanyFromContact = async (contactId, emailAccountId) => {
     .where(eq(contacts.id, contactId))
     .returning();
 
+  // Remove company assignment from existing emails for this contact
+  await db
+    .update(emails)
+    .set({
+      companyId: null,
+      updatedAt: new Date(),
+    })
+    .where(eq(emails.contactId, contactId));
+
   return updated;
 };
 
@@ -239,6 +260,15 @@ export const createCompanyFromContact = async (contactId, emailAccountId, userId
     .where(eq(contacts.id, contactId))
     .returning();
 
+  // Update existing emails for this contact to reference the new company
+  await db
+    .update(emails)
+    .set({
+      companyId: newCompany.id,
+      updatedAt: new Date(),
+    })
+    .where(eq(emails.contactId, contactId));
+
   return {
     company: newCompany,
     contact: updatedContact,
diff --git a/src/services/crm-email.service.js b/src/services/crm-email.service.js
index cce9231..4b42324 100644
--- a/src/services/crm-email.service.js
+++ b/src/services/crm-email.service.js
@@ -22,6 +22,7 @@ export const getEmailsForAccount = async (emailAccountId) => {
       sentByUserId: emails.sentByUserId,
       date: emails.date,
       createdAt: emails.createdAt,
+      companyId: emails.companyId,
       emailAccountId: emails.emailAccountId,
       contact: {
         id: contacts.id,
diff --git a/src/services/jmap.service.js b/src/services/jmap.service.js
index 0879993..570cba4 100644
--- a/src/services/jmap.service.js
+++ b/src/services/jmap.service.js
@@ -358,6 +358,12 @@ export const syncEmailsFromSender = async (
   try {
     logger.info(`Syncing emails with contact: ${senderEmail} for account ${emailAccountId}`);
 
+    const [contact] = await db
+      .select({ companyId: contacts.companyId })
+      .from(contacts)
+      .where(eq(contacts.id, contactId))
+      .limit(1);
+
     // Get Inbox and Sent mailboxes ONLY
     const mailboxes = await getMailboxes(jmapConfig);
     const inboxMailbox = mailboxes.find(m => m.role === 'inbox' || m.name === 'Inbox' || m.name === 'INBOX');
@@ -510,6 +516,7 @@ export const syncEmailsFromSender = async (
         await db.insert(emails).values({
           emailAccountId,
           contactId,
+          companyId: contact?.companyId || null,
           jmapId: email.id,
           messageId,
           threadId: email.threadId || messageId,
@@ -722,6 +729,7 @@ export const sendEmail = async (jmapConfig, userId, emailAccountId, to, subject,
     await db.insert(emails).values({
       emailAccountId,
       contactId: recipientContact?.id || null, // Link to contact if recipient is in contacts
+      companyId: recipientContact?.companyId || null,
       jmapId: createdEmailId,
       messageId,
       threadId: threadId || messageId,