144 lines
4.6 KiB
Markdown
144 lines
4.6 KiB
Markdown
# Crockery - simple email hosting
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## What
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* SMTP + IMAP email, plus bundled HTTP webmail client
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* Devoted to the task of serving email for a single domain
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* Can get its own valid TLS certificates via LE, or use supplied ones
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* Built-in anti-spam & anti-virus measures
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* Built-in DKIM support
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* Built-in DMARC support
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* Can tell you what DNS records you need, and check them for validity
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* Multiple email accounts for your domain
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* A "master" wildcard account (if desired)
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* Simple import from GMail, etc
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* Simple export to GMail, etc
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* Nice fast search
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* Interact with crockery with simple, natural-ish emails to do things
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* SMTP TLS verification - enabled by default
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* Try to email foo@shady.net - verification fails, email marked pending, fail in 7 days
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* Crockery emails user, "Yo. We can't send this email securely. Here are your options:"
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* User hits reply-to (goes to unique email address on same domain) saying what to do:
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* Cancel
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* Retry
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* Send just this email
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* Whitelist shady.net (pins certificate)
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* What other interactions might we like?
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## What not
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* JMAP. Not today.
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* Maildir/mbox support. Imports and exports via IMAP, backups by "copy this file"
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* Bring your own X (where X is MTA, IMAP server, database, etc, etc)
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* Multiple-domain support (maybe later)
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* CalDAV/Carddav (yet)
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* Externally sourced accounts (yet)
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* Sending email without having an account
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* Managesieve (for now)
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## Why
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Email architecture is really complicated, and setting up a mail server of your
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own is painful. Various projects exist to try to make it easier, eg:
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* iRedMail
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* docker-mailserver
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* symbiosis
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* ...
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(Personally, I had some ansible recipes: )
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Even among people who run their own websites, it's rare to run your own email.
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It's just too painful. Much of this pain is caused by ultra-configurable
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components that need to be orchestrated. Each has its own (remarkably obtuse)
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configuration language, and each can do far more than the common case for a
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small, single-domain site.
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So, let's make a single binary where all you have to do is:
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* Register a domain
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* Upload some DNS records
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* Run the binary
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and it gives you a sensible email setup without any additional configuration!
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If it has to share the domain with a HTTP server (quite common), allow the
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HTTP-specific parts of mail to be served via reverse proxying. This includes:
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* activesync push notifications
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* autodiscovery
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Probably other stuff. Email is big, and just keeps getting bigger.
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## How
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### Building a binary
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```
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$ go build ur.gs/crockery/cmd/crockery
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$ sudo setcap 'cap_net_bind_service=+ep' ./crockery
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```
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The second step allows crockery to bind to the various low-numbered ports it
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needs (25, 587, 149, 993) **without** running as root. Don't bother with it if
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you're going to be running crockery as root, e.g., as a container or a single-
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purpose system.
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### Initialize a new database
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```
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crockery init \
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--domain <domain-name> \
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--cert <cert-file> \
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--key <key-file> \
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--postmaster-password <password>
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```
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You can also provide the postmaster password in an environment variable:
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```
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CROCKERY_POSTMASTER_PASSWORD="<password>" crockery init --domain <domain-name> ---cert <cert-file> --key <key-file>
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```
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You can provide a custom database name with `--db <filename>`:
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```
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crockery --db foo.db init --domain <domain-name> ---cert <cert-file> --key <key-file>
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```
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### Run the server
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```
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./crockery run
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```
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Again, you can use `--db <filename>` if the default of `./crockery.db` doesn't
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suit. Crockery will load the configuration from the database and begin serving
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mail based on it. Received emails are also stored in the same file.
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### Configuration
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Mostly non-existent, aside from that listed above.
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We'll need to have a few *offline* commands baked into the `crockery` binary,
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apart from `init` as detailed above. Some ideas:
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```
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$ crockery change x y z (domain, user password, etc)
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$ crockery reindex (throw away existing indexes, regenerate)
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$ crockery whitelist tls <domain> (allow the domain to be sent to with insecure/no TLS)
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$ crockery whitelist receipt <domain> (bypass antispam for this domain)
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$ crockery blacklist receipt <domain> (no emails to be permitted from this domain
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```
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It's inconvenient for some of these functions to require the server to be
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offline, so we'll need to provide another configuration interface too.
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I like sending emails to it.
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Since we're going to need a HTTP server anyway, we could expose admin functions
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using that, if logged in as postmaster. It could also expose an API that the
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`crockery X` commands could connect to, rather than hitting the store directly.
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We can use the `.well-known` integration to avoid the need to configure there,
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too.
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