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/index</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 ?>