diff --git a/addons/account/models/account_invoice.py b/addons/account/models/account_invoice.py
index 5f2d83c5035..576f9d9e551 100644
--- a/addons/account/models/account_invoice.py
+++ b/addons/account/models/account_invoice.py
@@ -1834,5 +1834,5 @@ class MailComposeMessage(models.TransientModel):
             invoice = self.env['account.invoice'].browse(context['default_res_id'])
             if not invoice.sent:
                 invoice.sent = True
-            self = self.with_context(mail_post_autofollow=True)
+            self = self.with_context(mail_post_autofollow=True, lang=invoice.partner_id.lang)
         return super(MailComposeMessage, self).send_mail(auto_commit=auto_commit)
diff --git a/addons/purchase/models/purchase.py b/addons/purchase/models/purchase.py
index 53eeaffa2e3..8962513fd02 100644
--- a/addons/purchase/models/purchase.py
+++ b/addons/purchase/models/purchase.py
@@ -1131,6 +1131,7 @@ class MailComposeMessage(models.TransientModel):
     @api.multi
     def send_mail(self, auto_commit=False):
         if self._context.get('default_model') == 'purchase.order' and self._context.get('default_res_id'):
-            self = self.with_context(mail_post_autofollow=True)
+            order = self.env['purchase.order'].browse(self._context['default_res_id'])
+            self = self.with_context(mail_post_autofollow=True, lang=order.partner_id.lang)
             self.mail_purchase_order_on_send()
         return super(MailComposeMessage, self).send_mail(auto_commit=auto_commit)
diff --git a/addons/sale/wizard/mail_compose_message.py b/addons/sale/wizard/mail_compose_message.py
index 9ec46b48308..0291d3f848c 100644
--- a/addons/sale/wizard/mail_compose_message.py
+++ b/addons/sale/wizard/mail_compose_message.py
@@ -13,5 +13,5 @@ class MailComposeMessage(models.TransientModel):
             order = self.env['sale.order'].browse([self._context['default_res_id']])
             if order.state == 'draft':
                 order.with_context(tracking_disable=True).state = 'sent'
-            self = self.with_context(mail_post_autofollow=True)
+            self = self.with_context(mail_post_autofollow=True, lang=order.partner_id.lang)
         return super(MailComposeMessage, self).send_mail(auto_commit=auto_commit)