autodiscover

A single Go binary that replaces an nginx + PHP stack for serving email autodiscover responses. It reads a settings.json file and generates XML responses on the fly for multiple protocols and clients.

Supported Protocols and Clients

Protocol / Client	Endpoint	Format
Microsoft Outlook (POX Autodiscover)	POST /autodiscover/autodiscover.xml	POX XML
Microsoft Exchange ActiveSync	POST /autodiscover/autodiscover.xml	MobileSync XML
Thunderbird / Mozilla	GET /mail/config-v1.1.xml	clientConfig XML
Apple iOS / macOS	GET /profile.mobileconfig	Property List (.plist)
CalDAV (RFC 6764)	GET /.well-known/caldav	HTTP redirect
CardDAV (RFC 6764)	GET /.well-known/carddav	HTTP redirect
Matrix federation delegation	GET /.well-known/matrix/server	JSON (spec)
Matrix homeserver discovery	GET /.well-known/matrix/client	JSON (spec)

Building

You’ll need Go 1.23 or later.

To build for the current machine just do make build. To build for other architectures do something like make build-linux.

Running

./build/autodiscover-linux-amd64 -addr :8080 -config /path/to/settings.json

Flag	Default	Description
-addr	:8080	TCP address to listen on
-config	settings.json	Path to the JSON configuration file

Configuration (settings.json)

See example-settings.json for a complete example.

Top-level structure

Field	Type	Required	Description
info	object	yes	General provider information
server	object	yes	IMAP and SMTP server settings
ttl	integer	no	Time-to-live in hours for cached settings. Defaults to 1
matrix	object	no	Matrix well-known delegation targets
caldav	object	no	CalDAV server configuration
carddav	object	no	CardDAV server configuration
exchange	object	no	Microsoft Exchange Web Services URLs
activesync	object	no	Exchange ActiveSync endpoint URL
vpn	object	no	VPN configuration for Apple profiles
mdm	object	no	Mobile Device Management enrollment URL

info

Field	Type	Description
name	string	Human-readable provider name
url	string	Support or home page URL
domain	string	Primary mail domain

server.imap and server.smtp

Field	Type	Description
host	string	Server hostname or IP address
port	integer	TCP port number
socket	string	Encryption method: "SSL", "STARTTLS", or "plain"

server.domain_required

Field	Type	Description
domain_required	boolean	Whether the authentication domain is required

caldav and carddav

Field	Type	Description
host	string	DAV server hostname
port	integer	TCP port number
ssl	boolean	Whether to use HTTPS
principal_url	string	User-specific principal path. Supports placeholders %EMAILADDRESS%, %EMAILLOCALPART%, %EMAILDOMAIN%

matrix

Optional. When absent, both matrix endpoints return 404 with a plain-text explanation (which triggers SRV-based federation fallback).

Field	Type	Description
server	string	Value for m.server — the target homeserver hostname (or host:port) federation uses
homeserver	string	Value for m.homeserver.base_url, e.g. https://matrix.example.com
identity_server	string	Optional override for m.identity_server.base_url, defaults to homeserver

exchange

Field	Type	Description
ews_url	string	Exchange Web Services URL
oab_url	string	Offline Address Book URL
oof_url	string	Out of Office URL

activesync

Field	Type	Description
url	string	ActiveSync endpoint (e.g. https://mail.example.com/Microsoft-Server-ActiveSync)

vpn

Field	Type	Description
type	string	VPN type: "IKEv2", "L2TP", "PPTP", "IPSec", etc.
host	string	VPN server hostname
remote_id	string	Remote identifier (e.g. for IKEv2)
local_id	string	Local identifier (e.g. for IKEv2)
auth_method	string	Authentication method: "None", "Certificate", "SharedSecret", "Password"

mdm

Field	Type	Description
server_url	string	MDM enrollment server URL

Placeholders

The following placeholders are expanded in URLs where noted above:

Placeholder	Expands to
%EMAILADDRESS%	Full email address, e.g. user@example.com
%EMAILLOCALPART%	Local part, e.g. user
%EMAILDOMAIN%	Domain part, e.g. example.com

Apple Configuration Profile (/profile.mobileconfig)

When ?email=user@example.com is provided, the generated .mobileconfig includes payloads for all configured services:

• Email (com.apple.mail.managed) — IMAP incoming, SMTP outgoing
• CalDAV (com.apple.caldav.account)
• CardDAV (com.apple.carddav.account)
• VPN (com.apple.vpn.managed)
• MDM (com.apple.mdm)

Payload UUIDs are deterministically derived from the domain and payload type so they remain stable across restarts.

Well-known Redirects

The server responds to RFC 6764 .well-known requests with HTTP redirects to the configured DAV principal URLs:

Request	Redirect
GET /.well-known/caldav?email=user@example.com	307 = to expanded CalDAV principal URL
GET /.well-known/carddav?email=user@example.com	307 = to expanded CalDAV principal URL
GET /.well-known/matrix/server	200 = JSON with m.server
GET /.well-known/matrix/client	200 = JSON with homeserver/identity URLs