Deployed runtime: email, signatures, and billing

Capability	Environment variables	Dev / production rule
Email backend	NAVIGATOR_EMAIL_BACKEND	Must be sendgrid outside the harness
Outbound SendGrid	SENDGRID_API_KEY, SENDGRID_FROM_EMAIL	Required outside the harness
SendGrid base URL	SENDGRID_BASE_URL	Official hosts only outside the harness
Inbound SendGrid	SENDGRID_INBOUND_SECRET	Required outside the harness
Attachment scanner	NAVIGATOR_CLAMD_ADDR	Required in every deployed profile; private clamd only
Event webhook	SENDGRID_EVENTS_SECRET, SENDGRID_EVENTS_PUBLIC_KEY	Required outside the harness
Threaded mail	NAVIGATOR_PARSE_HOST, NAVIGATOR_LAWYER_NOTIFY_EMAIL	Both values enable it
DKIM fence	NAVIGATOR_DKIM_REQUIRE_DOMAIN	Optional domain pin
Internal ops notices	SLACK_WEBHOOK_URL	Optional; otherwise captured in memory
DocuSign endpoint	DOCUSIGN_BASE_URL	Declares DocuSign; demo in dev, live in production
DocuSign account	DOCUSIGN_ACCOUNT_ID	Environment-specific account
DocuSign JWT IDs	DOCUSIGN_INTEGRATION_KEY, DOCUSIGN_USER_ID	Preferred auth path
DocuSign JWT proof	DOCUSIGN_PRIVATE_KEY, DOCUSIGN_OAUTH_BASE	Preferred auth path
DocuSign static auth	DOCUSIGN_ACCESS_TOKEN	Short-lived fallback
DocuSign signer	DOCUSIGN_SIGNER_EMAIL, DOCUSIGN_SIGNER_NAME	Required signer identity
DocuSign webhook	DOCUSIGN_HMAC_KEY, DOCUSIGN_WEBHOOK_SECRET	Required once DOCUSIGN_BASE_URL is set
Xero tenant	XERO_TENANT_ID, XERO_BASE_URL	All Xero values select real billing
Xero OAuth client	XERO_CLIENT_ID, XERO_CLIENT_SECRET	Otherwise stub billing
Xero OAuth token	XERO_TOKEN_URL, XERO_SCOPE, XERO_ACCESS_TOKEN	Otherwise stub billing