global: move more config to env vars

.env

@@ -1,2 +1,21 @@
 # Required variables
-NOTESNOOK_API_SECRET= # This should be a randomly generated secret
+NOTESNOOK_API_SECRET= # This should be a randomly generated secret
+
+# S3 related variables for storing attachments
+S3_ACCESS_KEY=
+S3_ACCESS_KEY_ID=
+S3_SERVICE_URL=
+S3_REGION=
+
+# SMTP settings required for delivering emails
+SMTP_USERNAME=
+SMTP_PASSWORD=
+SMTP_HOST=
+SMTP_PORT=
+SMTP_REPLYTO_NAME= # optional
+SMTP_REPLYTO_EMAIL= # optional
+NOTESNOOK_SENDER_EMAIL= # optional
+NOTESNOOK_SENDER_NAME= # optional
+
+# MessageBird is used for 2FA via SMS
+MESSAGEBIRD_ACCESS_KEY=