diff --git a/.env_sample b/.env_sample
index c14c29212..5a122db17 100644
--- a/.env_sample
+++ b/.env_sample
@@ -155,3 +155,7 @@ STACK_EXCHANGE_APP_KEY=""
 # (https://docs.github.com/)
 GITHUB_KEY="Optional"
 GITHUB_SECRET="Optional"
+
+# For Sendgrid email
+# https://sendgrid.com/docs/for-developers/sending-email/upgrade-your-authentication-method-to-api-keys/#upgrade-to-api-keys-for-your-smtp-integration
+SENDGRID_API_KEY="Optional, Production only"
\ No newline at end of file