diff --git a/src/name-assignment/assignment-email.cpp b/src/name-assignment/assignment-email.cpp
new file mode 100644
index 0000000..685a820
--- /dev/null
+++ b/src/name-assignment/assignment-email.cpp
@@ -0,0 +1,62 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2017-2022, Regents of the University of California.
+ *
+ * This file is part of ndncert, a certificate management system based on NDN.
+ *
+ * ndncert is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation, either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * ndncert is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License along with
+ * ndncert, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndncert authors and contributors.
+ */
+
+#include "assignment-email.hpp"
+
+namespace ndncert {
+
+NDNCERT_REGISTER_FUNCFACTORY(AssignmentEmail, "email");
+
+AssignmentEmail::AssignmentEmail(const std::string& format)
+  : NameAssignmentFunc(format)
+{
+}
+
+std::vector<ndn::PartialName>
+AssignmentEmail::assignName(const std::multimap<std::string, std::string>& params)
+{
+  std::vector<ndn::PartialName> resultList;
+  Name result;
+  if (!m_nameFormat.empty() && params.count("email") > 0) {
+    const std::string& email = params.begin()->second;
+    auto formatIter = m_nameFormat.begin();
+    size_t emailSplit = email.rfind("@");
+    std::string domain = "." + email.substr(emailSplit + 1);
+
+    if (emailSplit != std::string::npos && emailSplit > 0) {
+      size_t domainSplit = domain.rfind(".");
+      while (domainSplit != std::string::npos) {
+        if (formatIter != m_nameFormat.end() && domain.substr(domainSplit + 1) == *formatIter) {
+          formatIter++;
+        }
+        else {
+          result.push_back(domain.substr(domainSplit + 1).c_str());
+        }
+        domain = domain.substr(0, domainSplit);
+        domainSplit = domain.rfind(".");
+      }
+      result.push_back(email.substr(0, emailSplit).c_str());
+      resultList.push_back(std::move(result));
+    }
+  }
+  return resultList;
+}
+
+} // namespace ndncert
diff --git a/src/name-assignment/assignment-email.hpp b/src/name-assignment/assignment-email.hpp
new file mode 100644
index 0000000..c0bb330
--- /dev/null
+++ b/src/name-assignment/assignment-email.hpp
@@ -0,0 +1,42 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2017-2022, Regents of the University of California.
+ *
+ * This file is part of ndncert, a certificate management system based on NDN.
+ *
+ * ndncert is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation, either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * ndncert is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License along with
+ * ndncert, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndncert authors and contributors.
+ */
+
+#ifndef NDNCERT_ASSIGNMENT_EMAIL_HPP
+#define NDNCERT_ASSIGNMENT_EMAIL_HPP
+
+#include "assignment-func.hpp"
+
+namespace ndncert {
+
+/**
+ * assign names base on client probe parameter
+ */
+class AssignmentEmail : public NameAssignmentFunc
+{
+public:
+  explicit AssignmentEmail(const std::string& format = "");
+
+  std::vector<ndn::PartialName>
+  assignName(const std::multimap<std::string, std::string>& params) override;
+};
+
+} // namespace ndncert
+
+#endif // NDNCERT_ASSIGNMENT_EMAIL_HPP
diff --git a/src/name-assignment/assignment-param.cpp b/src/name-assignment/assignment-param.cpp
index 956b3d8..e1961e7 100644
--- a/src/name-assignment/assignment-param.cpp
+++ b/src/name-assignment/assignment-param.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2017-2021, Regents of the University of California.
+ * Copyright (c) 2017-2022, Regents of the University of California.
  *
  * This file is part of ndncert, a certificate management system based on NDN.
  *
@@ -35,13 +35,17 @@
   std::vector<ndn::PartialName> resultList;
   Name result;
   for (const auto& item : m_nameFormat) {
-    auto it = std::find_if(params.begin(), params.end(),
-                           [&](const std::tuple<std::string, std::string>& e) { return std::get<0>(e) == item; });
-    if (it != params.end() && !it->second.empty()) {
-      result.append(it->second);
+    if (item.size() >= 2 && item[0] == '"' && item[item.size() - 1] == '"') {
+      result.append(item.substr(1, item.size() - 2));
     }
     else {
-      return resultList;
+      auto it = params.find(item);
+      if (it != params.end() && !it->second.empty()) {
+        result.append(it->second);
+      }
+      else {
+        return resultList; // empty
+      }
     }
   }
   resultList.push_back(std::move(result));