I have read and applied https://litmus.com/blog/fixing-table-alignment-in-yahoo-mail with no luck


  <table class="outer" bgcolor="#ffffff" align="center" style="background-color:#ffffff;border-spacing:0;font-family: Arial, sans-serif,'Montserrat';color:#ffffff;Margin:0 auto;width:100%;max-width:600px;table-layout: fixed; ">

<tr>
                    <td class="one-column" style="padding-top:0;padding-bottom:0;padding-right:0;padding-left:0;border-collapse: collapse;back">
                        <table width="100%" style="border-spacing:0;font-family:sans-serif;color:#ffffff; background-color:#DEDED0;border-collapse: collapse;  ">
                            <td background="http://static.cdn.responsys.net/i5/responsysimages/content/greensmoke/EM176_bg_a1.png" bgcolor="#176639" width="600" height="587" valign="top" style=" max-width:600px;background-repeat:no-repeat">
                                <!--[if gte mso 9]>
  <v:rect xmlns:v="urn:schemas-microsoft-com:vml" fill="true" stroke="false" style="width:600px;height:587px;">
    <v:fill type="tile" src="http://static.cdn.responsys.net/i5/responsysimages/content/greensmoke/EM176_bg_a1.png" color="#DEDED0" />
    <v:textbox inset="0,0,0,0">
  <![endif]-->
                                <div>

                                    <p style="Margin:0;font-size:40px;Margin-bottom:0px;font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif,'Work Sans';color:#176639;text-align: center; font-weight:800;padding-top:25px; letter-spacing: -3px">USE YOUR</p>
                                   <!--[if (gte mso 9)|(IE)]>
                        <table width="420" align="center">
                        <tr>
                        <td width="100%" valign="top" align="center">
                        <![endif]-->
                                    <table width="100%" cellspacing="0" cellpadding="0" style="border: 2px solid #DDDEDF; background-color: #ffffff;max-width:400px; text-align: center" align="center">
                                        <tr>
                                            <td align="center" style="Margin:0;font-weight:normal;font-size:40px;Margin-bottom:10px;font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif,'Work Sans';color:#176639;text-align: center; font-weight:400;padding-top:25px; letter-spacing: 1px;padding: 10px;color:#F95C1F" > 500 REWARDS POINTS</td>
                                        </tr>
                                    </table>
                                        <!--[if (gte mso 9)|(IE)]>
                        </td></tr></table>
                        <![endif]-->

                                    <h1 style="Margin:0;font-weight:normal;font-size:40px;Margin-bottom:10px;font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif,'Work Sans';color:#176639;text-align: center; font-weight:800;padding-top:5px; letter-spacing: -3px">NOW, BEFORE THEY EXPIRE</h1>

                                    <img src="http://static.cdn.responsys.net/i5/responsysimages/content/greensmoke/EM176_ProKit_1a.png" width="600" alt="Responsive Magic" style="border-width:0;width:100%;max-width:600px;height:auto;" />
                                    <p style="font-family:Arial, 'Helvetica Neue', Helvetica, sans-serif,'Montserrat';Margin:0;color:#000000;font-size:14px;Margin-bottom:15px; text-align:center;color:#ffffff;padding-left: 20px; padding-right: 20px">
                                        How about a new battery, pack of your favorite cartridges or a new carrying case? Use your rewards points toward a purchase.
                                        <br>
                                        <br> We just wanted to let you know that your [###] rewards points will expire in 2 weeks. Now’s a great time to take advantage of them and get yourself a great deal.
                                        <br>
                                        <br> You better hurry. Don't let those valuable rewards points go to waste!</p>


                                </div>
                                <!--[if gte mso 9]>
    </v:textbox>
  </v:rect>
  <![endif]-->
                            </td>
                        </table>
                    </td>


                </tr>

The table after the USE YOUR p tag is perfectly centered everywhere but YAHOO!!!

yahoo