Sending Mail Functionality When Clicking Button

   

def od_discount_approved(self, cr, uid, ids, context=None):
         self.write(cr,uid,ids,{'od_sales_man_discount_ctrl':False},context)
                               self.od_send_mail(cr,uid,ids,'rso_disc_approved_mail_to_salesperson',context=context)
        return True

    def od_send_mail(self,cr,uid,ids,template,context=None):
       
        ir_model_data = self.pool['ir.model.data']
        email_obj = self.pool.get('email.template')
        template_id = ir_model_data.get_object_reference(cr,uid,'orchid_rso', template)[1]
        sale_id = self.browse(cr,uid,ids,context) and self.browse(cr,uid,ids,context).id
        email_obj.send_mail(cr,uid,template_id,sale_id, force_send=True)
        return True

Through default data loading technic,you can create a template.

<record id="task_reviewer_mail" model="email.template">
            <field name="name">Task Reviewer Mail</field>
            <field name="email_from">${(user.email or '')|safe}</field>
            <field name="subject">Task</field>
            <field name="email_to">${object.reviewer_id.email}</field>
            <field name="model_id" ref="project.model_project_task"/>
          
            <field name="body_html"><![CDATA[
                <div style="font-family: 'Lucica Grande', Ubuntu, Arial, Verdana, sans-serif; font-size: 12px; color: rgb(34, 34, 34); background-color: #FFF; ">
                    <p>Dear ${object.reviewer_id.name or 'Reviewer'},</p>
                    <p>Please Check The task</p>
                  
                    <p>Thank You</p>
                   
                </div>           
            ]]></field>
        </record>
       
       
        <record id="task_creation_auto_mail_customer" model="email.template">
            <field name="name">Task Customer Mail</field>
            <field name="email_from">${(user.email or '')|safe}</field>
            <field name="subject">Task To Customer</field>
            <field name="email_to">${object.partner_id.email}</field>
            <field name="model_id" ref="project.model_project_task"/>
          
            <field name="body_html"><![CDATA[
                <div style="font-family: 'Lucica Grande', Ubuntu, Arial, Verdana, sans-serif; font-size: 12px; color: rgb(34, 34, 34); background-color: #FFF; ">
                    <p>Dear ${object.partner_id.name or 'Customer'},</p>
                    <p>Please Check</p>
                  
                    <p>Thank You</p>
                   
                </div>           
            ]]></field>
        </record>
       

        <record id="lead_to_opportunity_mail" model="email.template">
            <field name="name">Lead To Opportunity Mail</field>
            <field name="email_from">${(user.email or '')|safe}</field>
            <field name="subject">Lead To Opportunity</field>
            <field name="email_to">test@gmail.com</field>
            <field name="model_id" ref="crm.model_crm_lead"/>
          
            <field name="body_html"><![CDATA[
                <div style="font-family: 'Lucica Grande', Ubuntu, Arial, Verdana, sans-serif; font-size: 12px; color: rgb(34, 34, 34); background-color: #FFF; ">
                    <p>Dear ,</p>
                    <p>Please Check The task</p>
                  
                    <p>Thank You</p>
                   
                </div>           
            ]]></field>
        </record>





        <record id="disc_approved_mail_to_salesperson" model="email.template">
            <field name="name">Disc Approved Mail to Salesman</field>
            <field name="email_from">${(user.email or '')|safe}</field>
            <field name="subject">Discount Approved</field>
            <field name="email_to">test@gmail.com</field>
            <field name="model_id" ref="sale.model_sale_order"/>
          
            <field name="body_html"><![CDATA[
                <div style="font-family: 'Lucica Grande', Ubuntu, Arial, Verdana, sans-serif; font-size: 12px; color: rgb(34, 34, 34); background-color: #FFF; ">
                    <p>$Dear ${object.user_id.name or 'Salesman'},</p>
                    <p>Quotation No:${object.name or 'Quotation'}</p>
                  
                    <p>Thank You</p>
                   
                </div>           
            ]]></field>
        </record