diff --git a/DOCUMENTATION/SYSTEM_ADMINISTRATORS/CONFIGURE.md b/DOCUMENTATION/SYSTEM_ADMINISTRATORS/CONFIGURE.md
index f3ed5e589b..a0682b98dd 100644
--- a/DOCUMENTATION/SYSTEM_ADMINISTRATORS/CONFIGURE.md
+++ b/DOCUMENTATION/SYSTEM_ADMINISTRATORS/CONFIGURE.md
@@ -191,14 +191,19 @@ The ones that you may want to set are listed below for clarity.
     until they get their databases fixed up. See "UTF-8 database" above for
     details.
 
-* `schemacheck` (enum["runtime", "script"], default "runtime"): when to let
-    plugins check the database schema to add tables or update them. 'runtime'
-    can be costly (plugins check the schema on every hit, adding potentially
-    several db queries, some quite long), but not everyone knows how to run a
-    script or has the access in their hosting environment to do so. If you can,
-    set this to 'script' and run scripts/checkschema.php whenever you install
-    or upgrade a plugin.
+* `schemacheck` (enum["runtime", "script"], default "runtime"): when
+    to let plugins check the database schema to add tables or update
+    them. 'runtime' can be costly (plugins check the schema on every
+    hit, adding potentially several db queries, some quite long), but
+    not everyone knows how to run a script or has the access in their
+    hosting environment to do so. If you can, set this to 'script' and
+    run scripts/checkschema.php whenever you install or upgrade a
+    plugin.
 
+* `x-static-delivery` (string, default null): when a string, use this
+    as the header with wich to serve static files. Possible values are
+    'X-Sendfile' (for Apache and others) and 'X-Accel-Redirect' (for
+    nginx).
 
 syslog
 -------------------------------------------------------------------------------
diff --git a/actions/attachment.php b/actions/attachment.php
index a7e1c5d161..f261cc30bd 100644
--- a/actions/attachment.php
+++ b/actions/attachment.php
@@ -202,11 +202,16 @@ class AttachmentAction extends ManagedAction
     }
 
     /**
-     * Include $filepath in the response, for viewing and downloading
+     * Include $filepath in the response, for viewing and downloading.
+     * If provided, $filesize is used to size the HTTP request,
+     * otherwise it's value is calculated
      */
     static function sendFile(string $filepath, $filesize) {
-        if (common_config('site', 'use_x_sendfile')) {
-            header('X-Sendfile: ' . $filepath);
+        if (is_string(common_config('site', 'x-static-delivery'))) {
+            $relative_path = end(explode(INSTALLDIR, $filepath));
+            common_debug("Using Static Delivery with header: '" .
+                         common_config('site', 'x-static-delivery') . ": {$relative_path}'");
+            header(common_config('site', 'x-static-delivery') . ": {$relative_path}");
         } else {
             if (empty($filesize)) {
                 $filesize = filesize($filepath);
diff --git a/actions/attachment_thumbnail.php b/actions/attachment_thumbnail.php
index 8d4eb6f884..2a2ce61d94 100644
--- a/actions/attachment_thumbnail.php
+++ b/actions/attachment_thumbnail.php
@@ -84,6 +84,6 @@ class Attachment_thumbnailAction extends AttachmentAction
         header('Expires: 0');
         header('Content-Transfer-Encoding: binary');
 
-        AttachmentAction::sendFile($filepath, $size);
+        AttachmentAction::sendFile($filepath, $filesize);
     }
 }
diff --git a/lib/imagefile.php b/lib/imagefile.php
index 85747072a5..c6465c52b1 100644
--- a/lib/imagefile.php
+++ b/lib/imagefile.php
@@ -575,7 +575,7 @@ class ImageFile extends MediaFile
 
         $filename = basename($this->filepath);
         $extension = File::guessMimeExtension($this->mimetype);
-        $outname = "thumb-{$this->fileRecord->getID()}-{$width}x{$height}-{$filename}." . $extension;
+        $outname = "thumb-{$this->fileRecord->getID()}-{$width}x{$height}-{$filename}";
         $outpath = File_thumbnail::path($outname);
 
         // The boundary box for our resizing