Add msmtp for sending services emails

Dockerfile

@@ -33,7 +33,9 @@ FROM alpine:latest
 ARG ATHEME_UID
 ARG BUILD_CONTRIB_MODULES
 
-RUN apk add --no-cache openssl && (test -z "$BUILD_CONTRIB_MODULES" || apk add --no-cache libexecinfo)
+# openssl: used by some hashing and SASL algorithms
+# msmtp: used to route mail to an external mail server
+RUN apk add --no-cache openssl msmtp ca-certificates && (test -z "$BUILD_CONTRIB_MODULES" || apk add --no-cache libexecinfo)
 
 COPY --from=builder /atheme/ /atheme
 

README.md

@@ -2,7 +2,7 @@
 
 [![Build Status](https://drone.overdrivenetworks.com/api/badges/overdrivenetworks/atheme-docker/status.svg)](https://drone.overdrivenetworks.com/overdrivenetworks/atheme-docker)
 
-This is an unofficial Docker image for [Atheme IRC Services](https://github.com/atheme/atheme), based off of Alpine and rebuilt weekly.
+This is an unofficial Docker image for [Atheme IRC Services](https://github.com/atheme/atheme), based off of Alpine and built weekly.
 
 ## Usage
 
@@ -17,6 +17,12 @@ $ docker run -v /path/to/services/data:/atheme/etc ovdnet/atheme
 - You can use the `latest` tag (which points to the [latest release built from this repository](/.drone.yml)), or pin to a specific version (e.g. `7.2.10-r2`, `7.2`, `7`)
 - Builds with contrib modules are also available: `contrib` (latest release), as well as pins to specific versions (e.g. `7.2.10-r2-contrib`, `7.2-contrib`, `7-contrib`)
 
+### Sending mail from services
+
+This container bundles `msmtp` to easily route mail through an external provider. You can use it in Atheme by setting `mta = /usr/bin/msmtp` and mounting a configuration file into `/etc/msmtprc`.
+
+The Arch Linux Wiki has a useful page on msmtp configuration: https://wiki.archlinux.org/index.php/Msmtp#Basic_setup
+
 ## Build arguments
 
 For those who want to create customized builds, here are options exposed by the Dockerfile: