Postmoogle

more about that name

An Email to Matrix bridge. 1 room = 1 mailbox.

Postmoogle is an actual SMTP server that allows you to receive emails on your matrix server. It can't be used with arbitrary email providers, but setup your own provider "with matrix interface" instead.

Roadmap

Receive

• SMTP server
• Matrix bot
• Configuration in room's account data
• Receive emails to matrix rooms
• Receive attachments
• Map email threads to matrix threads

deep dive

features in that section considered as "nice to have", but not a priority

• DKIM verification
• SPF verification
• DMARC verification
• Blocklists

Send

• SMTP client
• Send a message to matrix room with special format to send a new email
• Reply to matrix thread sends reply into email thread

Configuration

1. Bot (mandatory)

env vars

• POSTMOOGLE_HOMESERVER - homeserver url, eg: https://matrix.example.com
• POSTMOOGLE_LOGIN - user login/localpart, eg: moogle
• POSTMOOGLE_PASSWORD - user password
• POSTMOOGLE_DOMAIN - SMTP domain to listen for new emails
• POSTMOOGLE_PORT - SMTP port to listen for new emails

other optional config parameters

• POSTMOOGLE_NOENCRYPTION - disable encryption support
• POSTMOOGLE_STATUSMSG - presence status message
• POSTMOOGLE_SENTRY_DSN - sentry DSN
• POSTMOOGLE_LOGLEVEL - log level
• POSTMOOGLE_DB_DSN - database connection string
• POSTMOOGLE_DB_DIALECT - database dialect (postgres, sqlite3)
• POSTMOOGLE_MAXSIZE - max email size (including attachments) in megabytes
• POSTMOOGLE_ADMINS - a space-separated list of admin users. See POSTMOOGLE_USERS for syntax examples

You can find default values in config/defaults.go

2. DNS (optional)

The following configuration needed only if you want to send emails using postmoogle

First, add new DMARC DNS record of TXT type for subdomain _dmarc with a proper policy, the easiest one is: v=DMARC1; p=quarantine;.

Example

$ dig txt _dmarc.DOMAIN

; <<>> DiG 9.18.6 <<>> txt _dmarc.DOMAIN
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57306
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;_dmarc.DOMAIN.			IN	TXT

;; ANSWER SECTION:
_dmarc.DOMAIN.		1799	IN	TXT	"v=DMARC1; p=quarantine;"

;; Query time: 46 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Sun Sep 04 21:31:30 EEST 2022
;; MSG SIZE  rcvd: 79

Second, add new SPF DNS record of TXT type for your domain that will be used with postmoogle, with format: v=spf1 ip4:SERVER_IP -all

Example

$ dig txt DOMAIN

; <<>> DiG 9.18.6 <<>> txt DOMAIN
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24796
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;DOMAIN.			IN	TXT

;; ANSWER SECTION:
DOMAIN.		1799	IN	TXT	"v=spf1 ip4:111.111.111.111 -all"

;; Query time: 36 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Sun Sep 04 21:35:04 EEST 2022
;; MSG SIZE  rcvd: 255

Third, add new MX DNS record of MX type for your domain that will be used with postmoogle, it should point to the same (sub-)domain. Looks odd, but some mail servers will refuse to interact with your mail server (and Postmoogle is already a mail server) without MX records.

Example

dig MX DOMAIN

; <<>> DiG 9.18.6 <<>> MX DOMAIN
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12688
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;DOMAIN.			IN	MX

;; ANSWER SECTION:
DOMAIN.		1799	IN	MX	10 DOMAIN.

;; Query time: 40 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Tue Sep 06 16:44:47 EEST 2022
;; MSG SIZE  rcvd: 59

Fourth (and the last one), add new DKIM DNS record of TXT type for subdomain postmoogle._domainkey that will be used with postmoogle.

You can get that signature using the !pm dkim command:

!pm dkim

DKIM signature is: v=DKIM1; k=ed25519; p=OcVzOwAONDfgbJX/5vwzlXOs9gUDO0YKlXHaDnBJtXw=. You need to add it to your DNS records (if not already): Add new DNS record with type = TXT, key (subdomain/from): postmoogle._domainkey and value (to):

v=DKIM1; k=ed25519; p=OcVzOwAONDfgbJX/5vwzlXOs9gUDO0YKlXHaDnBJtXw=

Without that record other email servers may reject your emails as spam, kupo.

Example

$ dig TXT postmoogle._domainkey.DOMAIN

; <<>> DiG 9.18.6 <<>> TXT postmoogle._domainkey.DOMAIN
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59014
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;postmoogle._domainkey.DOMAIN.	IN	TXT

;; ANSWER SECTION:
postmoogle._domainkey.DOMAIN. 600	IN TXT  "v=DKIM1; k=ed25519; p=OcVzOwAONDfgbJX/5vwzlXOs9gUDO0YKlXHaDnBJtXw="

;; Query time: 90 msec
;; SERVER: 1.1.1.1#53(1.1.1.1) (UDP)
;; WHEN: Mon Sep 05 16:16:21 EEST 2022
;; MSG SIZE  rcvd: 525

Usage

How to start

1. Invite the bot into a room you want to use as mailbox
2. Read the bot's introduction
3. Set mailbox using !pm mailbox NAME where NAME is part of email (e.g. NAME@example.com)
4. Done. Mailbox owner and other options will be set automatically when you configure mailbox. If you want to change them - check available options in the help message (!pm help)

Full list of available commands

• !pm help - Show help message
• !pm stop - Disable bridge for the room and clear all configuration

---

• !pm mailbox - Get or set mailbox of the room
• !pm owner - Get or set owner of the room

---

• !pm nosender - Get or set nosender of the room (true - hide email sender; false - show email sender)
• !pm nosubject - Get or set nosubject of the room (true - hide email subject; false - show email subject)
• !pm nohtml - Get or set nohtml of the room (true - ignore HTML in email; false - parse HTML in emails)
• !pm nothreads - Get or set nothreads of the room (true - ignore email threads; false - convert email threads into matrix threads)
• !pm nofiles - Get or set nofiles of the room (true - ignore email attachments; false - upload email attachments)

---

• !pm dkim - Get DKIM signature
• !pm users - Get or set allowed users patterns
• !pm mailboxes - Show the list of all mailboxes
• !pm delete <mailbox> - Delete specific mailbox

Where to get

docker registry, etke.cc