magento2 email header.html is not being included in transaction email

Question

I have created a transactional email in Admin, Marketing -> Email Templates.

Loaded in an email template from the Default Templates, but it's a custom module.

The template code loaded into the text area is:

{{template config_path="design/email/header_template"}}
            <!-- [ middle starts here] -->
            <table cellspacing="0" cellpadding="0" border="0" width="650">
                <tr>
                    <td valign="top">
                     content and vars -- all working fine
                    </td>
                </tr>
             </table>
{{template config_path="design/email/footer_template"}}

The actual template file is:

    {{template config_path="design/email/header_template"}}
            <!-- [ middle starts here] -->
            <table cellspacing="0" cellpadding="0" border="0" width="650">
                <tr>
                    <td valign="top">
                        <p><strong>Dear {{trans '%account_name' account_name=$customerName}}</strong>,<br/>
                        We have updated the point balance for you so that you can have relevant information of points earned or spent. To view more details, please click <a href="{{store url="rewardpoints"}}" style="color:#1E7EC8;">here</a>.</p>
                        <p style="border:1px solid #BEBCB7; padding:13px 18px; background:#F8F7F5; ">
                            <strong>The transaction detail</strong><br/>
                            <strong>Transaction title:</strong> {{var title}}<br/>
                            <strong>Transaction amount:</strong> {{var point_amount}}<br/>
                            <strong>Transaction status:</strong> {{var status}}<br/>
                            <strong>Current balance:</strong> {{var point_balance}}
                        <p>
                        <p>If you have any other questions, please feel free to contact us at <a href="mailto:{{config path='trans_email/ident_support/email'}}" style="color:#1E7EC8;">{{config path='trans_email/ident_support/email'}}</a> or call us at {{config path='general/store_information/phone'}} Monday - Friday, 8am - 5pm PST.</p>
                        <p>Thanks again,<br/>
                            <strong>{{trans '%STORE' STORE=$store.getFrontendName()}}</strong>
                        </p>
                    </td>
                </tr>

            </table>
    {{template config_path="design/email/footer_template"}}

And when I preview the template, the headers and footers show, however when the email is sent out, it's not showing the header or footer just the content.

Answer 1

I was confused by this as well, as I had the same issue.

However - upon investigation, I found it was actually the email client I was using. Thunderbird. I cleared the cache within that, and emails loaded as expected.