diff --git a/plugins/platforms/email/adapter.py b/plugins/platforms/email/adapter.py
index e7c57746f..3961d8123 100644
--- a/plugins/platforms/email/adapter.py
+++ b/plugins/platforms/email/adapter.py
@@ -159,14 +159,16 @@ def _is_automated_sender(address: str, headers: dict) -> bool:
     return False
     
 def check_email_requirements() -> bool:
-    """Check if email platform dependencies are available."""
-    addr = os.getenv("EMAIL_ADDRESS")
-    pwd = os.getenv("EMAIL_PASSWORD")
-    imap = os.getenv("EMAIL_IMAP_HOST")
-    smtp = os.getenv("EMAIL_SMTP_HOST")
-    if not all([addr, pwd, imap, smtp]):
-        return False
-    return True
+    """Check if email platform settings are available and non-blank.
+
+    Treats blank/whitespace-only values as missing so an abandoned setup that
+    left empty ``EMAIL_*`` keys in ``.env`` does not enable the platform (#40715).
+    """
+    addr = os.getenv("EMAIL_ADDRESS", "").strip()
+    pwd = os.getenv("EMAIL_PASSWORD", "").strip()
+    imap = os.getenv("EMAIL_IMAP_HOST", "").strip()
+    smtp = os.getenv("EMAIL_SMTP_HOST", "").strip()
+    return all([addr, pwd, imap, smtp])
 
 
 def _decode_header_value(raw: str) -> str:
@@ -418,10 +420,19 @@ class EmailAdapter(BasePlatformAdapter):
             if not value
         ]
         if missing:
-            logger.error(
-                "[Email] Not configured — missing %s. Set it via `hermes gateway "
-                "setup` (env) or platforms.email in config.yaml.",
-                ", ".join(missing),
+            message = (
+                "Not configured — missing "
+                + ", ".join(missing)
+                + ". Set it via `hermes gateway setup` (env) or platforms.email "
+                "in config.yaml."
+            )
+            logger.error("[Email] %s", message)
+            # Mark non-retryable so the gateway does NOT keep reconnecting against
+            # an empty host. A blank-but-present env var (e.g. ``EMAIL_IMAP_HOST=``)
+            # used to slip past the startup gate and drive an indefinite retry
+            # loop that leaked memory until the host OOM-killed (#40715).
+            self._set_fatal_error(
+                "email_missing_configuration", message, retryable=False
             )
             return False
 
diff --git a/tests/gateway/test_email.py b/tests/gateway/test_email.py
index 37f62eb5d..613e42378 100644
--- a/tests/gateway/test_email.py
+++ b/tests/gateway/test_email.py
@@ -1436,7 +1436,8 @@ class TestConnectionConfigResolution(unittest.TestCase):
         self.assertEqual(adapter._address, "hermes@test.com")
 
     def test_connect_aborts_without_attempting_imap_when_host_missing(self):
-        """A missing host returns False without the cryptic DNS error."""
+        """A missing host returns False without the cryptic DNS error, and marks
+        the failure non-retryable so the gateway stops reconnecting (#40715)."""
         import asyncio
         from gateway.config import PlatformConfig
         from plugins.platforms.email.adapter import EmailAdapter
@@ -1453,6 +1454,32 @@ class TestConnectionConfigResolution(unittest.TestCase):
 
         self.assertFalse(result)
         mock_imap.assert_not_called()
+        # The OOM fix (#40715): a blank host must NOT leave the platform in the
+        # retryable reconnect loop — it is a permanent config error.
+        self.assertTrue(adapter.has_fatal_error)
+        self.assertEqual(adapter.fatal_error_code, "email_missing_configuration")
+        self.assertFalse(adapter.fatal_error_retryable)
+        self.assertIn("EMAIL_IMAP_HOST", adapter.fatal_error_message or "")
+
+    def test_blank_present_env_vars_are_not_required(self):
+        """Blank/whitespace EMAIL_* values must read as missing (#40715) — an
+        abandoned setup with empty keys must not enable the platform."""
+        from plugins.platforms.email.adapter import check_email_requirements
+        for blank in ("", "   ", "\n"):
+            with patch.dict(os.environ, {
+                "EMAIL_ADDRESS": blank, "EMAIL_PASSWORD": blank,
+                "EMAIL_IMAP_HOST": blank, "EMAIL_SMTP_HOST": blank,
+            }, clear=False):
+                self.assertFalse(check_email_requirements())
+
+    def test_all_settings_present_satisfies_requirements(self):
+        """The connected check passes only when all four settings are non-blank."""
+        from plugins.platforms.email.adapter import check_email_requirements
+        with patch.dict(os.environ, {
+            "EMAIL_ADDRESS": "hermes@test.com", "EMAIL_PASSWORD": "secret",
+            "EMAIL_IMAP_HOST": "imap.test.com", "EMAIL_SMTP_HOST": "smtp.test.com",
+        }, clear=False):
+            self.assertTrue(check_email_requirements())
 
 
 if __name__ == "__main__":