diff --git a/swh/vault/api/server.py b/swh/vault/api/server.py
--- a/swh/vault/api/server.py
+++ b/swh/vault/api/server.py
@@ -74,14 +74,7 @@
     vcfg.update(vcfg.get("args", {}))
 
     # Default to top-level value if any
-    if "cache" not in vcfg:
-        vcfg["cache"] = cfg.get("cache")
-    if "storage" not in vcfg:
-        vcfg["storage"] = cfg.get("storage")
-    if "scheduler" not in vcfg:
-        vcfg["scheduler"] = cfg.get("scheduler")
-    if "client_max_size" not in vcfg:
-        vcfg["client_max_size"] = cfg.get("client_max_size")
+    vcfg = {**cfg, **vcfg}
 
     for key in ("cache", "storage", "scheduler"):
         if not vcfg.get(key):
diff --git a/swh/vault/backend.py b/swh/vault/backend.py
--- a/swh/vault/backend.py
+++ b/swh/vault/backend.py
@@ -73,7 +73,7 @@
         self.cache = VaultCache(**config["cache"])
         self.scheduler = get_scheduler(**config["scheduler"])
         self.storage = get_storage(**config["storage"])
-        self.smtp_server = smtplib.SMTP()
+        self.smtp_server = smtplib.SMTP(**config.get("smtp", {}))
 
         db_conn = config["db"]
         self._pool = psycopg2.pool.ThreadedConnectionPool(