diff --git a/addons/account/account_invoice.py b/addons/account/account_invoice.py
index 0d392d85fa2..288f1119639 100644
--- a/addons/account/account_invoice.py
+++ b/addons/account/account_invoice.py
@@ -213,6 +213,7 @@ class account_invoice(osv.osv):
             \n* The \'Open\' state is used when user create invoice,a invoice number is generated.Its in open state till user does not pay invoice. \
             \n* The \'Paid\' state is set automatically when the invoice is paid. Its related journal entries may or may not be reconciled. \
             \n* The \'Cancelled\' state is used when user cancel invoice.'),
+        'sent': fields.boolean('Sent', readonly=True, help="It indicates that the invoice has been sent."),
         'date_invoice': fields.date('Invoice Date', readonly=True, states={'draft':[('readonly',False)]}, select=True, help="Keep empty to use the current date"),
         'date_due': fields.date('Due Date', states={'paid':[('readonly',True)], 'open':[('readonly',True)], 'close':[('readonly',True)]}, select=True,
             help="If you use payment terms, the due date will be computed automatically at the generation "\
@@ -287,6 +288,7 @@ class account_invoice(osv.osv):
         'check_total': 0.0,
         'internal_number': False,
         'user_id': lambda s, cr, u, c: u,
+        'sent': False,
     }
     _sql_constraints = [
         ('number_uniq', 'unique(number, company_id, journal_id, type)', 'Invoice Number must be unique per Company!'),
@@ -641,6 +643,7 @@ class account_invoice(osv.osv):
             'move_name':False,
             'internal_number': False,
             'period_id': False,
+            'sent': False,
         })
         if 'date_invoice' not in default:
             default.update({
diff --git a/addons/account/account_invoice_view.xml b/addons/account/account_invoice_view.xml
index c6926ce742e..152dae5de8b 100644
--- a/addons/account/account_invoice_view.xml
+++ b/addons/account/account_invoice_view.xml
@@ -262,15 +262,15 @@
             <field name="arch" type="xml">
                 <form layout="manual">
                 <div class="oe_form_topbar">
-                	<button name="action_invoice_sent" type="object" string="Send by Email" states="open"/>
-                	<button name="invoice_print" string="Print Invoice" type="object" states="open"/>
+                	<button name="action_invoice_sent" type="object" string="Send by Email" states="open" attrs="{'invisible':['|',('sent','=',True), ('state', '=', 'draft')]}"/>
+                	<button name="invoice_print" string="Print Invoice" type="object" states="open" attrs="{'invisible':['|',('sent','=',True), ('state', '=', 'draft')]}"/>
                     <button name="invoice_open" states="draft,proforma2" string="Validate"/>
                     <button name="invoice_proforma2" states="draft" string="PRO-FORMA" groups="account.group_proforma_invoices"/>
                     <button name="%(action_account_invoice_refund)d" type='action' string='Refund Invoice' states='sent,paid'/>
                     <button name="invoice_cancel" states="draft,proforma2,sale,open,sent" string="Cancel" groups="base.group_no_one"/>
                     <button name="action_cancel_draft" states="cancel" string="Reset to Draft" type="object"/>
                     <button name='%(action_account_state_open)d' type='action' string='Re-Open' groups="account.group_account_invoice" attrs="{'invisible':['|', ('state','&lt;&gt;','paid'), ('reconciled', '=', True)]}" help="This button only appears when the state of the invoice is 'paid' (showing that it has been fully reconciled) and auto-computed boolean 'reconciled' is False (depicting that it's not the case anymore). In other words, the invoice has been dereconciled and it does not fit anymore the 'paid' state. You should press this button to re-open it and let it continue its normal process after having resolved the eventual exceptions it may have created."/>
-                    <button name="%(account_invoices)d" string="Print Invoice" type="action" states="open,paid,proforma,sale,proforma2"/>
+                    <!--button name="%(account_invoices)d" string="Print Invoice" type="action" states="open,paid,proforma,sale,proforma2"/-->
                     <div class="oe_right">
                         <field name="state" widget="statusbar" nolabel="1" statusbar_visible="draft,open,sent,paid" statusbar_colors='{"proforma":"blue","proforma2":"blue"}'/>
                     </div>
@@ -293,6 +293,7 @@
                     <newline/>
                     <field domain="[('company_id', '=', company_id),('type','=', 'receivable')]" name="account_id" groups="account.group_account_user"/>
                     <field name="name"/>
+                    <field name="sent"/>
                     </group>
                     <notebook colspan="4">
                         <page string="Invoice">
diff --git a/addons/account/account_invoice_workflow.xml b/addons/account/account_invoice_workflow.xml
index 88028fc2ca1..9f676df393d 100644
--- a/addons/account/account_invoice_workflow.xml
+++ b/addons/account/account_invoice_workflow.xml
@@ -34,7 +34,7 @@ invoice_validate()</field>
         <record id="act_sent" model="workflow.activity">
             <field name="wkf_id" ref="wkf"/>
             <field name="name">sent</field>
-            <field name="action">write({'state':'sent'})</field>
+            <field name="action">write({'state':'sent', 'sent':True})</field>
             <field name="kind">function</field>
         </record>
 
diff --git a/addons/account/account_report.xml b/addons/account/account_report.xml
index 78caf1c95b6..7b574c8960e 100644
--- a/addons/account/account_report.xml
+++ b/addons/account/account_report.xml
@@ -21,7 +21,7 @@
             string="Invoices"
             attachment="(object.state in ('open','paid')) and ('INV'+(object.number or '').replace('/','')+'.pdf')"
             usage="default"
-            multi="True"/>
+            />
         <report id="account_transfers" model="account.transfer" name="account.transfer" string="Transfers" xml="account/report/transfer.xml" xsl="account/report/transfer.xsl"/>
         <report auto="False" id="account_intracom" menu="False" model="account.move.line" name="account.intracom" string="IntraCom"/>