diff --git a/config/settings.py b/config/settings.py
index b531b34..cad53bd 100644
--- a/config/settings.py
+++ b/config/settings.py
@@ -226,7 +226,13 @@ EMAIL_HOST_USER = os.getenv("EMAIL_HOST_USER", "")      # set on deploy platform
 EMAIL_HOST_PASSWORD = os.getenv("EMAIL_HOST_PASSWORD", "")  # set on deploy platform
 EMAIL_USE_TLS = os.getenv("EMAIL_USE_TLS", "true").lower() == "true"
 EMAIL_USE_SSL = os.getenv("EMAIL_USE_SSL", "false").lower() == "true"
-DEFAULT_FROM_EMAIL = os.getenv("DEFAULT_FROM_EMAIL", "")
+# === FROM-ADDRESS ===
+# Where outgoing emails appear to come from. If DEFAULT_FROM_EMAIL isn't
+# explicitly set, fall back to the Gmail address we authenticate as —
+# that's always a valid sender since it's the same account sending the email.
+# Without this fallback, emails fail with "Invalid address ''" if the
+# env var is missing, even though auth + SMTP are otherwise fine.
+DEFAULT_FROM_EMAIL = os.getenv("DEFAULT_FROM_EMAIL", "") or EMAIL_HOST_USER
 CONTACT_EMAIL_TO = [
     item.strip()
     for item in os.getenv("CONTACT_EMAIL_TO", DEFAULT_FROM_EMAIL).split(",")