Offline publishing

Offline payloads let people send email through RelaySMS Mail without linking an account; linked accounts need none of this (settings). The app encrypts an offline payload to the server’s identity key, and the Publisher publishes it through the rmail adapter, which must be installed. Anyone who can reach an allowed protocol can send one.

Each payload is tagged with the protocol it arrived on:

• https: REST POST /v1/publications

• smtp: the SMTP transport

• An offline payload from a protocol not in OFFLINE_PUBLISH_ALLOWED_PROTOCOLS is discarded.

• An offline payload over https must carry OFFLINE_PUBLISH_SHARED_SECRET in the request’s tag field, or it’s discarded.

• Leaving OFFLINE_PUBLISH_ALLOWED_PROTOCOLS empty, or listing https, without the secret fails manage.sh check, and the services refuse to start.

• A discarded payload is logged and recorded as failed in the publication stats, with reason protocol_not_allowed, offline_tag_missing or offline_tag_invalid. POST /v1/publications still returns success, since the check runs in the queue.

Allowing https

1. Generate a secret:

   openssl rand -hex 32
   

2. Set OFFLINE_PUBLISH_SHARED_SECRET to it, and add https to OFFLINE_PUBLISH_ALLOWED_PROTOCOLS, such as smtp,https.

3. Check and restart:

   sudo ./manage.sh check
   sudo ./manage.sh restart
   

Next steps

Connect each relay that posts over https with the secret as its tag (FORWARD_TAG for Twilio).