commit 7189e33b8051873b1469a5e00cf1f85a787feb67
parent 292e145f719aca9973658e36f8d63875099d61ec
Author: Brian C. Lane <bcl@brianlane.com>
Date: Tue, 31 Dec 2019 09:31:56 -0800
Add README.md
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+# letterbox - SMTP to Maildir delivery agent
+
+This is a simple Go program that accepts SMTP connections and delivers mail to
+a per-user maildir directory. I use it to gather reports from various services
+on my LAN without needing to setup postfix or some other more complex MTA.
+
+ Usage of letterbox:
+ -config string
+ Path to configutation file (default "letterbox.toml")
+ -host string
+ Host IP or name to bind to
+ -maildirs string
+ Path to the top level of the user Maildirs (default "/var/spool/maildirs")
+ -port int
+ Port to bind to (default 25)
+
+The configuration file is written using
+[TOML](https://github.com/toml-lang/toml). You must specify at least one
+host/network and one email otherwise delivery will fail. For example:
+
+ hosts = ["192.168.1.0/24", "127.0.0.1", "logger.mydomain.com"]
+ emails = ["root@mydomain.com", "user@another.com"]
+
+If the connection is not from an allowed host the connection will be refused.
+Destination emails must be listed in the `emails` list. The user portion of the
+email will be used to create a new maildir under the `-maildirs` path. For
+example, sending an email to user@another.com will create a new maildir at
+`/var/spool/maildirs/user`.
+
+# WARNING
+
+This code is not meant to be run on the open network. Make sure it is protected behind a firewall,
+and is running as an un-privileged user. *Never* run it as root.
