diff --git a/test/minimail.py b/test/minimail.py
index 689b6f4..a6a5a77 100644
--- a/test/minimail.py
+++ b/test/minimail.py
@@ -6,15 +6,61 @@
 # this file is under GNU General Public License 3.0
 
 
-import pEp
 from secrets import token_urlsafe
+from itertools import compress
+from functools import partial
+from time import sleep
+
+
+def unlock(inbox):
+    lockfile = inbox / "lock"
+    try:
+        lockfile.unlink()
+    except:
+        pass
+
+
+class Lock:
+    def __init__(self, inbox):
+        self.inbox = inbox
+
+    def __exit__(self, *exc):
+        unlock(self.inbox)
+
+    def __enter__(self):
+        lockfile = self.inbox / "lock"
+        while lockfile.is_file():
+            sleep(1)
+        lockfile.touch()
 
 
 def send(inbox, msg):
-    name = token_urlsafe(16) + ".eml"
-    with open(inbox / name, "wb") as f:
-        f.write(str(msg).encode())
+    with Lock(inbox):
+        name = token_urlsafe(16) + ".eml"
+        with open(inbox / name, "wb") as f:
+            f.write(str(msg).encode())
+
+
+def newer(file1, file2):
+    if not file2.is_file():
+        return False
+    elif not file1.is_file():
+        return True
+
+    stat1 = file1.stat()
+    stat2 = file2.stat()
+    return stat2.st_mtime > stat1.st_mtime
+
 
+def recv_all(inbox, marker):
+    with Lock(inbox):
+        r = []
+        while not r:
+            for f in compress(inbox.glob("*.eml"), partial(newer, file1=marker)):
+                t = f.readall()
+                r.append(t)
+            if not r:
+                sleep(1)
+        marker.touch(exist_ok=True)
+    return r
 
-def recv(inbox):
-    pass
diff --git a/test/sync_test.py b/test/sync_test.py
index a29efc2..a520b7e 100644
--- a/test/sync_test.py
+++ b/test/sync_test.py
@@ -60,7 +60,6 @@ EINTR = 4
 
 if __name__ == "__main__":
     from optparse import OptionParser
-    from multiprocessing import Process
 
     optParser = OptionParser()
     optParser.add_option("-c", "--clean", action="store_true", dest="clean",
@@ -68,11 +67,16 @@ if __name__ == "__main__":
     options, args = optParser.parse_args()
 
     if options.clean:
+        from minimail import unlock
+
         rmrf("TestInbox")
+        unlock(pathlib.Path("TestInbox"))
         rmrf("Alice")
         rmrf("Barbara")
 
     else:
+        from multiprocessing import Process
+
         os.makedirs("TestInbox", exist_ok=True)
         setup("Alice")
         setup("Barbara")