Make the mail check synchronous

amonit/check/mail.py

 import imaplib
 import smtplib
 import os
+import time
 
 from email.mime import text, multipart
 
@@ -39,34 +40,11 @@ def send_then_receive(context, account_from, account_to):
     """ Send a mail using SMTP, then check that it is received using IMAP
     This is useful either on a single server or across servers to ensure
     SMTP works properly from server to server.
-
-    The canary is first sent, then looked for in the next execution.
     """
-    # First check the canary if any
-    result = {"up": False, "message": ""}
-    if "canary" in context:
-        canary = context["canary"]
-        try:
-            client = get_imap_client(
-                account_to["host"], account_to.get("port", 143),
-                account_to.get("encrypt", None)
-            )
-            client.login(account_to["username"], account_to["password"])
-            client.select(account_to["inbox"])
-            filter = f'(UNSEEN SUBJECT "{canary}")'
-            status, data = client.uid("search", None, filter)
-            if status == "OK":
-                for uid in data[0].split():
-                    client.uid("store", uid, "+FLAGS", "(\\Seen)")
-                    result["up"] = True
-            if not result["up"]:
-                domain = account_to["username"].split("@")[1]
-                result["message"] = f"message not delivered to {domain}"
-            client.logout()
-        except Exception as error:
-            result = {"up": False, "message": str(error)}
-    # Then drop a new canary
+    # Generate and store a canary
     canary = os.urandom(8).hex()
+    result = {"canary": canary}
+    # First send an email
     smtp = get_smtp_client(
         account_from["host"], account_from.get("port", 587),
         account_from.get("encrypt", None)
@@ -83,5 +61,30 @@ def send_then_receive(context, account_from, account_to):
         message.as_string()
     )
     smtp.quit()
-    result["canary"] = canary
+    start_time = time.time()
+    # Then wait for the delivery
+    client = get_imap_client(
+        account_to["host"], account_to.get("port", 143),
+        account_to.get("encrypt", None)
+    )
+    client.login(account_to["username"], account_to["password"])
+    client.select(account_to["inbox"])
+    filter_string = f'(UNSEEN SUBJECT "{canary}")'
+    for _ in range(10):
+        status, data = client.uid("search", None, filter_string)
+        delay = int(time.time() - start_time)
+        print(status, data)
+        if status == "OK" and data[0]:
+            for uid in data[0].split():
+                client.uid("store", uid, "+FLAGS", "(\\Seen)")
+            result["up"] = True
+            result["delay"] = delay
+            result["message"] = f"message delivered in {delay} seconds"
+            break
+        time.sleep(10)
+    else:
+        result["up"] = False
+        domain = account_to["username"].split("@")[1]
+        result["message"] = f"message not delivered to {domain}"
+    # Return the result
     return result