diff --git a/src/builtin_actions.py b/src/builtin_actions.py
index e54eb2f..c107bec 100644
--- a/src/builtin_actions.py
+++ b/src/builtin_actions.py
@@ -956,6 +956,17 @@ async def action_mark_email_boundaries(owner: str, **kwargs) -> Tuple[str, bool]
         return str(e), False
 
 
+# Sender local-parts (matched exactly or by prefix) whose mail never carries a
+# personal signature worth learning. These compare against the local-part
+# (before "@"), so role names must NOT include a trailing "@" — "support@" etc.
+# could never match a local-part of "support" and were silently dead.
+_SIG_SKIP_PREFIXES = (
+    "noreply", "no-reply", "donotreply", "do-not-reply",
+    "mailer-daemon", "notifications", "notification", "bounce",
+    "newsletter", "support", "info", "admin",
+)
+
+
 async def action_learn_sender_signatures(owner: str, **kwargs) -> Tuple[str, bool]:
     """For each sender with ≥3 recent inbox emails, ask the LLM to extract
     the common signature block across their messages. The cached sig is
@@ -1013,16 +1024,11 @@ async def action_learn_sender_signatures(owner: str, **kwargs) -> Tuple[str, boo
             return "No emails to scan", True
 
         # 2. Group by sender; drop addresses that don't carry useful sigs.
-        SKIP_PREFIXES = (
-            "noreply", "no-reply", "donotreply", "do-not-reply",
-            "mailer-daemon", "notifications", "notification", "bounce",
-            "newsletter", "support@", "info@", "admin@",
-        )
         by_sender: dict[str, list[dict]] = {}
         for m in mails:
             addr = m["from_address"]
             local = addr.split("@", 1)[0]
-            if any(local == p or local.startswith(p) for p in SKIP_PREFIXES):
+            if any(local == p or local.startswith(p) for p in _SIG_SKIP_PREFIXES):
                 continue
             # Skip plus-aliases / list-style addresses too.
             if "+" in local or "-noreply" in addr or "-bounces" in addr:
diff --git a/tests/test_sender_signature_skip_roles.py b/tests/test_sender_signature_skip_roles.py
new file mode 100644
index 0000000..e7270a3
--- /dev/null
+++ b/tests/test_sender_signature_skip_roles.py
@@ -0,0 +1,35 @@
+"""Sender-signature learning must skip role addresses like support@/info@.
+
+The skip-list compares against the email local-part (before "@"), but the
+entries were written "support@", "info@", "admin@" — which can never equal or
+prefix a local-part of "support"/"info"/"admin", so those role senders were
+NOT skipped and the LLM wasted work learning signatures from them. The entries
+must omit the "@".
+"""
+from src.builtin_actions import _SIG_SKIP_PREFIXES
+
+
+def _skipped(addr):
+    local = addr.split("@", 1)[0]
+    return any(local == p or local.startswith(p) for p in _SIG_SKIP_PREFIXES)
+
+
+def test_role_addresses_are_skipped():
+    assert _skipped("support@vendor.com")
+    assert _skipped("info@company.com")
+    assert _skipped("admin@example.org")
+
+
+def test_noreply_style_still_skipped():
+    assert _skipped("noreply@x.com")
+    assert _skipped("mailer-daemon@x.com")
+    assert _skipped("newsletter@x.com")
+
+
+def test_real_person_is_not_skipped():
+    assert not _skipped("john.smith@x.com")
+    assert not _skipped("alice@x.com")
+
+
+def test_no_skip_entry_contains_at():
+    assert all("@" not in p for p in _SIG_SKIP_PREFIXES)