server: handle multipart/mixed with an html or text subpart

server/src/graphql.rs

@@ -325,6 +325,14 @@ fn extract_mixed(m: &ParsedMail) -> Result<Body, Error> {
             return extract_related(sp);
         }
     }
+    for sp in &m.subparts {
+        let body = sp.get_body()?;
+        match sp.ctype.mimetype.as_str() {
+            "text/plain" => return Ok(Body::PlainText(PlainText { text: body })),
+            "text/html" => return Ok(Body::Html(Html { html: body })),
+            _ => (),
+        }
+    }
     Err("extract_mixed".into())
 }