server

// server is a SMTP server that is simple to setup and use.
//
// The binary is the main server, this server is responsible to receive your
// emails and save them according to your hooks. As well as sending them.
//
// # Setting up your email server
//
// Email works in a complex way, DNS records must match your server's
// configuration. This guide will try to give more detailed information
// in comparison with the website tutorial.
//
// An email server typically listens on ports 25, 2525, 587 or 465 for mail
// exchange. But their use differ:
//
//   - 25: is the original SMTP port and first to be official by RFC.
//   - 465: is marked as deprecated.
//   - 587: is also official by RFC, this port is used for TLS encrypted mail.
//
// The current recomendation is to use port 587. Dovel works with any port,
// and the value must be set in the port field of the config file. To
// configure this server see [Config].
//
// # Server configuration
//
// This section is dedicated to help you correctly run your dover server. The
// configuration is done using a single config file which should be located
// in $XDG_CONFIG_DIR/dovel/config.json which normaly expands to
// ~/.config/dovel/config.json. 
// The structure of this config file is [model.Config]. See that doc for more
// details. The following example should be enough to receive emails:
//
//	{
//		"Port": "2525",
//		"Domain": "my.domain",
//		"ReadTimeout": 30,
//		"WriteTimeout": 30,
//		"MaxMessageBytes": 5000000,
//		"MaxRecipients": 5,
//		"Certificate": "fullchain.pem",
//		"PrivateKey": "privkey.pem"
//	}
//
// Note that Certificate and PrivateKey are given so that your server can use
// TLS connections, this is desired for enhanced security. In cases where
// proxies are used in front of servers, for doing the TLS handshake, setting
// certificates here is not necessary.
//
// # Receiving emails
//
// To receive email the MX record must be correctly set on your registrar,
// make sure it is pointing to your server where dover is running. Everytime
// dovel receives an email it searches for an executable file in
// $XDG_CONFIG_DIR/dovel/hooks/ named receive-DOMAIN, for the DOMAIN receiving
// the email and executes it passing the email in mbox format as standard
// input. Then it is up to the script to decide what to do. See the scripts
// repo for examples, one simple is given in the next section.
//
// # Hooks
//
// A simple hook is a shell script that simply concatenates the received email
// to a .mbox file, e.g. to receive email for your domain create a file named
// receive-<DOMAIN> in the hooks folder with the following content:
//
//	#!/bin/sh
//	cat >> ~/mail/dovel.mbox
//
// Be sure to make the file executable. Now whenever an email to the domain
// DOMAIN it will be appended to the ~/mail/dovel.mbox file, which you can
// later open and read.
//
// # Configuring DNS records
//
// To receive emails you need to setup the MX record in your domain registrar,
// sending email is more complicated, some receiving servers only need the SPF
// and PTR records, some also need DKIM and DMARC, adjust according to your
// needs. Configuring DNS records is not the goal of this doc.
//
// # DKIM configuration
//
// DKIM in dovel is handled in a per-user basis only for sending emails,
// for receiving emails it is up to the corresponding hook. This means that
// each user have to setup its DKIM key. Luckily this is simply pointing
// the key path in the [User] struct.
//
// # Sending email
//
// Dovel also sends email, for that it needs a valid VaultFile path on the
// config. That means you need at least one user described on the json file.
// The format of that file is a JSON array of the [model.User] struct. Here's
// one example:
//
// 	[
// 		{
// 			"Name": "user1@my.domain",
// 			"PrivateKey": "dkim.priv",
// 			"Password": "1234"
// 		}
// 	]
//
// This means the user1@my.domain is allowed to send emails, also as its DKIM
// key was passed it will be used to sign the email using the DKIM guidelines.
// This is optional.
//
// You can use any email client to communicate with your dovel server. When an
// email comes from the domain configured, Dovel will known you want to send
// the email, and will check if the sending user is valid using the configured
// users, in positive case the email is sent, and the hook named send-<DOMAIN>
// for the domain used is run passing the sent email as input.
// The success of this hook does not impact one the sent email, it is mainly
// used for storing it.
//
// # Debuging your server
//
// Dovel will issue debugging logs for the developer's convenience by setting
// the DEBUG environment variable to any non-empty value at the time the server
// is started, e.g.:
//
//	DEBUG=1 ./server
//
package main