diff --git a/src/client/components/components-web-view.vala b/src/client/components/components-web-view.vala
index f49ebb0a..6896a6b8 100644
--- a/src/client/components/components-web-view.vala
+++ b/src/client/components/components-web-view.vala
@@ -79,9 +79,12 @@ public abstract class Components.WebView : WebKit.WebView, Geary.BaseInterface {
                                         File cache_dir) {
         WebsiteDataManager data_manager = new WebsiteDataManager(cache_dir.get_path());
         WebKit.WebContext context = new WebKit.WebContext.with_website_data_manager(data_manager);
-        // Use the doc viewer model since each web view instance only
-        // ever shows a single HTML document.
-        context.set_cache_model(WebKit.CacheModel.DOCUMENT_VIEWER);
+        // Enable WebProcess sandboxing
+        context.add_path_to_sandbox(web_extension_dir.get_path(), true);
+        context.set_sandbox_enabled(true);
+        // Use the doc browser model so that we get some caching of
+        // resources between email body loads.
+        context.set_cache_model(WebKit.CacheModel.DOCUMENT_BROWSER);
 
         context.register_uri_scheme("cid", (req) => {
                 WebView? view = req.get_web_view() as WebView;