web-relay is an smtp relay accessible from websites. The purpose is to allow client-side javascript applications to send e-mails without polyfills etc. Security obviously is a big issue with stuff like this (think spam), so I'm trying to implement as many filters as makes sense in order to close down the relay for unauthorized access.

1. Download source
2. Get dependencies (kingpin) with go get in source directory
3. Build with go build
4. Start resulting binary

usage: web-relay --bindaddr=BINDADDR --server=SERVER [<flags>]

Flags:
  --help               Show context-sensitive help (also try --help-long and --help-man).
  --bindaddr=BINDADDR  Address this server should bind to.
  --server=SERVER      Target relay mail server.
  --secret=""          Secret required to access server.

The client has access to two API endpoints

• /plain accepts POST requests for simple and plain (non-templated) e-mails
• /template accepts POST requests for templated e-mails

Shared POST fields are:

• secret: simple (and bad) authentication
• from: required exactly once, sender e-mail address
• to: required once or more, receiver e-mail address(es)
• subject: required exactly once, e-mail subject
• message: required exactly once, e-mail body

The templated endpoint also expects the parameter values that is required once or more and holds a row of values for each instance of the template. Each row follows the format "name"="value"[,more...].

(✓ indicates "implemented", ✗ indicates "missing")

• ✓ plain + templated mails (templates are expanded on the server to save bandwidth)
• ✓ shared secret authorization
• ✗ filter by sender
• ✗ other nice filters

This project is licensed under MIT license which allows use of this application for non-commercial as well as commercial use. See LICENSE for more information.