Revision 7b92f6ee-698a-40ed-9a5a-bb166ce869a1

Add below files into your custom module 

Ex:-Namespace:- Mytest Modulename : Myemail;  

1. Create customer_account.xml into Mytest/Myemail/view/frontend/layout

        <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
            <body>
                <referenceBlock name="customer_account_navigation">
                    <block class="Magento\Framework\View\Element\Html\Link\Current" name="customer-account-navigation-myemail">
                        <arguments>
                            <argument name="path" xsi:type="string">myemail/customer</argument>
                            <argument name="label" xsi:type="string"> MyEmail</argument>
                        </arguments>
                    </block>
                </referenceBlock>
            </body>
         </page>

2. Create myemail_customer_index.xml into Mytest/Myemail/view/frontend/layout

        <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../../../lib/internal/Magento/Framework/View/Layout/etc/page_configuration.xsd">
            <update handle="customer_account"/>
            <body>
                <referenceBlock name="page.main.title">
                    <action method="setPageTitle">
                        <argument translate="true" name="title" xsi:type="string">MyEmail</argument>
                    </action>
                 </referenceBlock>
                 <referenceContainer name="content">
                     <block class="Magento\Framework\View\Element\Template" name="my_email" template="Mytest_Myemail::test.phtml">
                     </block>
                </referenceContainer>
            </body>
        </page>

3. Create Index.php into Mytest/Myemail/Controller/Customer

   

        <?php
        namespace Mytest\Myemail\Controller\Customer;
        
        class Index extends \Magento\Framework\App\Action\Action {
        
         public function execute() {
        
            $this->_view->loadLayout();
        
            $this->_view->renderLayout();
          }
        
        }

4. Create test.phtml into Mytest/Myemail/view/frontend/templates

        <?php // Add some code ?>

5. Put routes.xml into folder Mytest/Myemail/etc/frontend with the following inside: 

        <?xml version="1.0"?> 
        <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc‌/routes.xsd">
            <router id="standard"> 
                <route id="myemail" frontName="myemail"> 
                    <module name="Mytest_Myemail" /> 
                </route> 
            </router> 
        </config>