go-main-autoconf - Simple mail client configuration

This is a simple mail client configuration server that provides auto-configuration for mail clients. It is written in Go and uses the gofiber package to serve the configuration files.

It provides mailbox configuration for Apple's Mobileconfig, Microsoft's Autodiscover & Mozilla's Thunderbird.

Note: This is a work in progress and is not yet ready for production use.
And current is it only tested with Thunderbird.

Installation

Fetch latest binaries for the proper OS from the releases page.

On Ubuntu 22.04

Copy the binary to /usr/local/bin.

Create a user for the service:

adduser --no-create-home --no-shell --disabled-login --group go-mail-autoconf go-mail-autoconf

Create a systemd service file /etc/systemd/system/go-mail-autoconf.service:

[Unit]
Description=Go instance to server mail auto configuration
After=network.target

[Service]
Type=simple
EnvironmentFile=/etc/default/go-mail-autoconf
User=go-mail-autoconf
Group=nogroup
ExecStart=/usr/local/bin/go-mail-autoconf
Restart=on-failure

[Install]
WantedBy=multi-user.target

Create a configuration file /etc/default/go-mail-autoconf eg.:

IMAP_SERVER=mail.dummy.org
SMTP_SERVER=mail.dummy.org
SERVER_URL=127.0.0.1:30090

Reload systemd and start the service:

systemctl daemon-reload
systemctl enable go-mail-autoconf
systemctl start go-mail-autoconf

Nginx site configuration '/etc/nginx/sites-available/go-mail-autoconf' eg.:

server {
        listen 80;
        server_name autoconfig.<FQDN> autoconfig.* maildiscovery.* autodiscovery.* autodiscover.*;
        location ~* ^/(autodiscover/autodiscover|mail/config|email\.mobileconfig) {
                proxy_pass http://127.0.0.1:30090;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header Host $http_host;
                proxy_set_header X-Forwarded-Proto $scheme;
                proxy_buffering off;
        }

        location / {
                return 404;
        }
}

server {
        server_name autoconfig.network-it.dk autoconfig.* maildiscovery.* autodiscovery.* autodiscover.*;
        location ~* ^/(autodiscover/autodiscover|mail/config|email\.mobileconfig) {
                proxy_pass http://127.0.0.1:30090;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header Host $http_host;
                proxy_set_header X-Forwarded-Proto $scheme;
                proxy_buffering off;
        }

        location / {
                return 404;
        }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/autoconfig.<FQDN>/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/autoconfig.<FQDN>/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}

The <FQDN> should be replaced with the fully qualified domain. And certbot is used to manage the SSL certificates.

Environment variables

The following environment variables are used to configure the server:

Variable	Description	Default
IMAP_SERVER	Hostname of the IMAP server	imap.dummy.org
IMAP_PORT	Port of the IMAP server	993
IMAP_SSL	Use SSL for IMAP	true
POP3_SERVER	Hostname of the POP3 server
POP3_PORT	Port of the POP3 server	995
POP3_SSL	Use SSL for POP3	true
SMTP_SERVER	Hostname of the SMTP server	smtp.dummy.org
SMTP_PORT	Port of the SMTP server	587
SMTP_SSL	Use SSL for SMTP	false
SMTP_GLOBAL_PREFERRED	Use the SMTP server as the global preferred server	false
EMAIL_PROVIDER	Domain of the email provider	dummy.org
SERVER_URL	URL of the server	127.0.0.1:3000

References

This code is inspired by the following article https://pipo.blog/articles/20210826-email-autoconf and GitLab repository https://gitlab.com/onlime/email-autoconf by Philip Iezzi.