<p>
Google Takeout, good for backup of gmail, or anything else from the Google-verse.
</p>
<ul>
<li><a href="https://www.google.com/takeout/">https://www.google.com/takeout/</a>
</li>
</ul>

<p>
Thunderbird email client
</p>
<ul>
<li><a href="https://www.mozilla.org/en-US/thunderbird/">https://www.mozilla.org/en-US/thunderbird/</a>
</li>
</ul>

<p>
ImportExportTools for Thunderbird
</p>
<ul>
<li><a href="https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/">https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/</a>
</li>
</ul>