diff --git a/cmping.py b/cmping.py
index a7e6a76..fb977a7 100644
--- a/cmping.py
+++ b/cmping.py
@@ -39,6 +39,12 @@
 from deltachat_rpc_client import DeltaChat, EventType, Rpc
 from xdg_base_dirs import xdg_cache_home
 
+
+class CMPingError(Exception):
+    """Raised when cmping encounters a non-recoverable error during probing."""
+    pass
+
+
 # Spinner characters for progress display
 SPINNER_CHARS = ["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏"]
 
@@ -192,7 +198,11 @@ def main():
     if not args.relay2:
         args.relay2 = args.relay1
 
-    pinger = perform_ping(args)
+    try:
+        pinger = perform_ping(args)
+    except CMPingError as e:
+        print(f"\r✗ {e}")
+        raise SystemExit(1)
     expected_total = pinger.sent * args.numrecipients
     raise SystemExit(0 if pinger.received == expected_total else 1)
 
@@ -298,8 +308,7 @@ def setup_accounts(args, sender_maker, receiver_maker):
         profiles_created += 1
         print_progress("Setting up profiles", profiles_created, total_profiles, profiles_created)
     except Exception as e:
-        print(f"\r✗ Failed to setup sender profile on {args.relay1}: {e}")
-        sys.exit(1)
+        raise CMPingError(f"Failed to setup sender profile on {args.relay1}: {e}") from e
 
     # Create receiver accounts
     receivers = []
@@ -310,8 +319,9 @@ def setup_accounts(args, sender_maker, receiver_maker):
             profiles_created += 1
             print_progress("Setting up profiles", profiles_created, total_profiles, profiles_created)
         except Exception as e:
-            print(f"\r✗ Failed to setup receiver profile {i+1} on {args.relay2}: {e}")
-            sys.exit(1)
+            raise CMPingError(
+                f"Failed to setup receiver profile {i+1} on {args.relay2}: {e}"
+            ) from e
 
     # Profile setup complete
     print_progress("Setting up profiles", done=True)
@@ -531,8 +541,9 @@ def wait_online_thread():
     wait_thread.join()
 
     if online_error:
-        print(f"\n✗ Timeout or error waiting for profiles to be online: {online_error}")
-        sys.exit(1)
+        raise CMPingError(
+            f"Timeout or error waiting for profiles to be online: {online_error}"
+        ) from online_error
 
     print_progress("Waiting for profiles to be online", done=True)
 
@@ -572,15 +583,23 @@ def wait_online_thread(maker):
         t.join()
 
     if online_errors:
-        print(f"\n✗ Timeout or error waiting for profiles to be online: {online_errors[0]}")
-        sys.exit(1)
+        raise CMPingError(
+            f"Timeout or error waiting for profiles to be online: {online_errors[0]}"
+        ) from online_errors[0]
 
     print_progress("Waiting for profiles to be online", done=True)
 
 
-def perform_ping(args):
+def perform_ping(args, accounts_dir=None, timeout=None):
     """Main ping execution function with timing measurements.
 
+    Args:
+        args: Namespace with relay1, relay2, count, interval, verbose,
+              numrecipients, reset attributes.
+        accounts_dir: Optional base directory for account storage.
+              Defaults to $XDG_CACHE_HOME/cmping. Override this to isolate
+              concurrent probes (each needs its own DB to avoid locking).
+
     Timing Phases:
     1. account_setup_time: Time to create and configure all accounts
     2. group_join_time: Time for all receivers to join the group
@@ -588,8 +607,17 @@ def perform_ping(args):
 
     Returns:
         Pinger: The pinger object with results
+            Also has account_setup_time, group_join_time, message_time (float, seconds)
+            and results list of (seq, ms_duration, receiver_idx) tuples.
+
+    Raises:
+        CMPingError: On account setup or connectivity failures.
     """
-    base_accounts_dir = xdg_cache_home().joinpath("cmping")
+    if accounts_dir is not None:
+        from pathlib import Path
+        base_accounts_dir = Path(accounts_dir)
+    else:
+        base_accounts_dir = xdg_cache_home().joinpath("cmping")
     
     # Determine unique relays being tested. Using a set to deduplicate when
     # relay1 == relay2 (same relay testing), so we only create one RPC context.
@@ -660,6 +688,8 @@ def perform_ping(args):
         message_start = time.time()
 
         pinger = Pinger(args, sender, group, receivers)
+        if timeout is not None:
+            pinger.deadline = time.time() + timeout
         received = {}
         # Track current sequence for output formatting
         current_seq = None
@@ -670,6 +700,7 @@ def perform_ping(args):
                 if seq not in received:
                     received[seq] = []
                 received[seq].append(ms_duration)
+                pinger.results.append((seq, ms_duration, receiver_idx))
 
                 # Track timing for this sequence
                 if seq not in seq_tracking:
@@ -753,6 +784,11 @@ def perform_ping(args):
             recv_rate = pinger.received / message_time
             print(f"recv rate: {recv_rate:.2f} msg/s")
 
+        # Store timing data on pinger
+        pinger.account_setup_time = account_setup_time
+        pinger.group_join_time = group_join_time
+        pinger.message_time = message_time
+
         return pinger
     finally:
         # Clean up all RPC contexts
@@ -803,9 +839,17 @@ def __init__(self, args, sender, group, receivers):
         )
         ALPHANUMERIC = string.ascii_lowercase + string.digits
         self.tx = "".join(random.choices(ALPHANUMERIC, k=30))
-        t = threading.Thread(target=self.send_pings, daemon=True)
         self.sent = 0
         self.received = 0
+        self.results = []  # list of (seq, ms_duration, receiver_idx)
+        self.account_setup_time = 0.0
+        self.group_join_time = 0.0
+        self.message_time = 0.0
+        # Optional wall-clock deadline for the messaging phase. When set,
+        # send_pings() stops sending and receive() stops waiting at this time.
+        # Set externally (e.g. by perform_ping) after setup phases complete.
+        self.deadline = None
+        t = threading.Thread(target=self.send_pings, daemon=True)
         t.start()
 
     @property
@@ -818,15 +862,21 @@ def send_pings(self):
 
         Each message contains: unique_id timestamp sequence_number
         Flow: Sender -> SMTP relay1 -> IMAP relay2 -> All receivers
+
+        Respects self.deadline: stops sending early when the wall clock passes
+        the deadline so we don't fire pings we'll never wait for.
         """
         for seq in range(self.args.count):
+            if self.deadline is not None and time.time() >= self.deadline:
+                break
             text = f"{self.tx} {time.time():.4f} {seq:17}"
             self.group.send_text(text)
             self.sent += 1
             time.sleep(self.args.interval)
         # we sent all pings, let's wait a bit, then force quit if main didn't finish
-        time.sleep(60)
-        os.kill(os.getpid(), signal.SIGINT)
+        if self.deadline is None:
+            time.sleep(60)
+            os.kill(os.getpid(), signal.SIGINT)
 
     def receive(self):
         """Receive ping messages from all receivers.
@@ -867,6 +917,8 @@ def receiver_thread(receiver_idx, receiver):
             threads.append(t)
 
         while num_pending > 0:
+            if self.deadline is not None and time.time() >= self.deadline:
+                break
             try:
                 receiver_idx, receiver, event = event_queue.get(timeout=1.0)
                 if event is None: