diff --git a/platform/clojure/mailchecker.clj b/platform/clojure/mailchecker.clj
index 5264c7ec..efac1bcd 100644
--- a/platform/clojure/mailchecker.clj
+++ b/platform/clojure/mailchecker.clj
@@ -38,17 +38,16 @@
   [string]
   (str/split string #"\."))
 
-(defn top-domain-part
-  "Returns the top domain for email"
+(defn all-domain-suffixes
+  "Returns all suffixes of the email domain, longest first"
   [email]
-  (dot-join
-    (take-last 2
-      (dot-split (domain-part email)))))
+  (let [domain-parts (dot-split (domain-part email))]
+       (map #(dot-join (drop % domain-parts)) (range 0 (count domain-parts)))))
 
 (defn in-blacklist?
-  "Returns true if email domain is not in the blacklist"
+  "Returns true if any suffix of the email domain is in the blacklist"
   [email]
-  (contains? blacklist (top-domain-part email)))
+  (some (partial contains? blacklist) (all-domain-suffixes email)))
 
 (defn valid?
   "Returns true if the email is valid"
diff --git a/platform/clojure/mailchecker.tmpl.clj b/platform/clojure/mailchecker.tmpl.clj
index 70e2dcd2..5fe591e9 100644
--- a/platform/clojure/mailchecker.tmpl.clj
+++ b/platform/clojure/mailchecker.tmpl.clj
@@ -38,17 +38,16 @@
   [string]
   (str/split string #"\."))
 
-(defn top-domain-part
-  "Returns the top domain for email"
+(defn all-domain-suffixes
+  "Returns all suffixes of the email domain, longest first"
   [email]
-  (dot-join
-    (take-last 2
-      (dot-split (domain-part email)))))
+  (let [domain-parts (dot-split (domain-part email))]
+       (map #(dot-join (drop % domain-parts)) (range 0 (count domain-parts)))))
 
 (defn in-blacklist?
-  "Returns true if email domain is not in the blacklist"
+  "Returns true if any suffix of the email domain is in the blacklist"
   [email]
-  (contains? blacklist (top-domain-part email)))
+  (some (partial contains? blacklist) (all-domain-suffixes email)))
 
 (defn valid?
   "Returns true if the email is valid"
diff --git a/test/platform.clojure.test.clj b/test/platform.clojure.test.clj
index 1c3e3637..22a29639 100644
--- a/test/platform.clojure.test.clj
+++ b/test/platform.clojure.test.clj
@@ -5,35 +5,50 @@
 (ns clojure.test.example
   (:use clojure.test))
 
+(defn expect-valid-result [expected-valid email]
+  (is (= expected-valid (mailchecker/valid? email))))
+
+(def expect-invalid (partial expect-valid-result false))
+(def expect-valid (partial expect-valid-result true))
+
 ; Valid
 (deftest true-for-valid-1
-  (is (= true (mailchecker/valid? "plop@plop.com"))))
+  (expect-valid "plop@plop.com"))
 (deftest true-for-valid-2
-  (is (= true (mailchecker/valid? "my.ok@ok.plop.com"))))
+  (expect-valid "my.ok@ok.plop.com"))
 (deftest true-for-valid-3
-  (is (= true (mailchecker/valid? "my+ok@ok.plop.com"))))
+  (expect-valid "my+ok@ok.plop.com"))
 (deftest true-for-valid-4
-  (is (= true (mailchecker/valid? "my=ok@ok.plop.com"))))
+  (expect-valid "my=ok@ok.plop.com"))
 (deftest true-for-valid-5
-  (is (= true (mailchecker/valid? "ok@gmail.com"))))
+  (expect-valid "ok@gmail.com"))
 (deftest true-for-valid-6
-  (is (= true (mailchecker/valid? "ok@hotmail.com"))))
+  (expect-valid "ok@hotmail.com"))
 
 ; Invalid
 (deftest false-for-invalid-1
-  (is(= false (mailchecker/valid? "plopplop.com"))))
+  (expect-invalid "plopplop.com"))
 (deftest false-for-invalid-2
-  (is(= false (mailchecker/valid? "my+ok@ok=plop.com"))))
+  (expect-invalid "my+ok@ok=plop.com"))
 (deftest false-for-invalid-3
-  (is(= false (mailchecker/valid? "my,ok@ok.plop.com"))))
+  (expect-invalid "my,ok@ok.plop.com"))
 
 (deftest false-for-spam-1
-  (is(= false (mailchecker/valid? "ok@tmail.com"))))
+  (expect-invalid "ok@tmail.com"))
 (deftest false-for-spam-2
-  (is(= false (mailchecker/valid? "ok@33mail.com"))))
+  (expect-invalid "ok@33mail.com"))
 (deftest false-for-spam-3
-  (is(= false (mailchecker/valid? "ok@ok.33mail.com"))))
+  (expect-invalid "ok@ok.33mail.com"))
 (deftest false-for-spam-4
-  (is(= false (mailchecker/valid? "ok@guerrillamailblock.com"))))
+  (expect-invalid "ok@guerrillamailblock.com"))
+
+(deftest false-for-blacklist-entries
+  (every? (fn [domain]
+              (do (expect-invalid (str "test@" domain))
+                  (expect-invalid (str "test@subdomain." domain))
+                  ;; Blacklisted domains should be valid as subdomains of a
+                  ;; valid domain.
+                  (expect-valid (str "test@" domain ".gmail.com"))))
+          mailchecker/blacklist))
 
 (run-all-tests)