the imap & smtp servers now allow logging in with tls client authentication and
the "external" sasl authentication mechanism. email clients like thunderbird,
fairemail, k9, macos mail implement it. this seems to be the most secure among
the authentication mechanism commonly implemented by clients. a useful property
is that an account can have a separate tls public key for each device/email
client. with tls client cert auth, authentication is also bound to the tls
connection. a mitm cannot pass the credentials on to another tls connection,
similar to scram-*-plus. though part of scram-*-plus is that clients verify
that the server knows the client credentials.
for tls client auth with imap, we send a "preauth" untagged message by default.
that puts the connection in authenticated state. given the imap connection
state machine, further authentication commands are not allowed. some clients
don't recognize the preauth message, and try to authenticate anyway, which
fails. a tls public key has a config option to disable preauth, keeping new
connections in unauthenticated state, to work with such email clients.
for smtp (submission), we don't require an explicit auth command.
both for imap and smtp, we allow a client to authenticate with another
mechanism than "external". in that case, credentials are verified, and have to
be for the same account as the tls client auth, but the adress can be another
one than the login address configured with the tls public key.
only the public key is used to identify the account that is authenticating. we
ignore the rest of the certificate. expiration dates, names, constraints, etc
are not verified. no certificate authorities are involved.
users can upload their own (minimal) certificate. the account web interface
shows openssl commands you can run to generate a private key, minimal cert, and
a p12 file (the format that email clients seem to like...) containing both
private key and certificate.
the imapclient & smtpclient packages can now also use tls client auth. and so
does "mox sendmail", either with a pem file with private key and certificate,
or with just an ed25519 private key.
there are new subcommands "mox config tlspubkey ..." for
adding/removing/listing tls public keys from the cli, by the admin.
bstore was updated to v0.0.6 to add this logging.
this simplifies some of the db-handling code in mtastsdb,tlsrptdb,dmarcdb. we
now call the package-level Init() and Close() in all tests properly.
for applications to compose/send messages, receive delivery feedback, and
maintain suppression lists.
this is an alternative to applications using a library to compose messages,
submitting those messages using smtp, and monitoring a mailbox with imap for
DSNs, which can be processed into the equivalent of suppression lists. but you
need to know about all these standards/protocols and find libraries. by using
the webapi & webhooks, you just need a http & json library.
unfortunately, there is no standard for these kinds of api, so mox has made up
yet another one...
matching incoming DSNs about deliveries to original outgoing messages requires
keeping history of "retired" messages (delivered from the queue, either
successfully or failed). this can be enabled per account. history is also
useful for debugging deliveries. we now also keep history of each delivery
attempt, accessible while still in the queue, and kept when a message is
retired. the queue webadmin pages now also have pagination, to show potentially
large history.
a queue of webhook calls is now managed too. failures are retried similar to
message deliveries. webhooks can also be saved to the retired list after
completing. also configurable per account.
messages can be sent with a "unique smtp mail from" address. this can only be
used if the domain is configured with a localpart catchall separator such as
"+". when enabled, a queued message gets assigned a random "fromid", which is
added after the separator when sending. when DSNs are returned, they can be
related to previously sent messages based on this fromid. in the future, we can
implement matching on the "envid" used in the smtp dsn extension, or on the
"message-id" of the message. using a fromid can be triggered by authenticating
with a login email address that is configured as enabling fromid.
suppression lists are automatically managed per account. if a delivery attempt
results in certain smtp errors, the destination address is added to the
suppression list. future messages queued for that recipient will immediately
fail without a delivery attempt. suppression lists protect your mail server
reputation.
submitted messages can carry "extra" data through the queue and webhooks for
outgoing deliveries. through webapi as a json object, through smtp submission
as message headers of the form "x-mox-extra-<key>: value".
to make it easy to test webapi/webhooks locally, the "localserve" mode actually
puts messages in the queue. when it's time to deliver, it still won't do a full
delivery attempt, but just delivers to the sender account. unless the recipient
address has a special form, simulating a failure to deliver.
admins now have more control over the queue. "hold rules" can be added to mark
newly queued messages as "on hold", pausing delivery. rules can be about
certain sender or recipient domains/addresses, or apply to all messages pausing
the entire queue. also useful for (local) testing.
new config options have been introduced. they are editable through the admin
and/or account web interfaces.
the webapi http endpoints are enabled for newly generated configs with the
quickstart, and in localserve. existing configurations must explicitly enable
the webapi in mox.conf.
gopherwatch.org was created to dogfood this code. it initially used just the
compose/smtpclient/imapclient mox packages to send messages and process
delivery feedback. it will get a config option to use the mox webapi/webhooks
instead. the gopherwatch code to use webapi/webhook is smaller and simpler, and
developing that shaped development of the mox webapi/webhooks.
for issue #31 by cuu508
we don't want external software to include internal details like mlog.
slog.Logger is/will be the standard.
we still have mlog for its helper functions, and its handler that logs in
concise logfmt used by mox.
packages that are not meant for reuse still pass around mlog.Log for
convenience.
we use golang.org/x/exp/slog because we also support the previous Go toolchain
version. with the next Go release, we'll switch to the builtin slog.
we were already accepting, processing and displaying incoming tls reports. now
we start tracking TLS connection and security-policy-related errors for
outgoing message deliveries as well. we send reports once a day, to the
reporting addresses specified in TLSRPT records (rua) of a policy domain. these
reports are about MTA-STS policies and/or DANE policies, and about
STARTTLS-related failures.
sending reports is enabled by default, but can be disabled through setting
NoOutgoingTLSReports in mox.conf.
only at the end of the implementation process came the realization that the
TLSRPT policy domain for DANE (MX) hosts are separate from the TLSRPT policy
for the recipient domain, and that MTA-STS and DANE TLS/policy results are
typically delivered in separate reports. so MX hosts need their own TLSRPT
policies.
config for the per-host TLSRPT policy should be added to mox.conf for existing
installs, in field HostTLSRPT. it is automatically configured by quickstart for
new installs. with a HostTLSRPT config, the "dns records" and "dns check" admin
pages now suggest the per-host TLSRPT record. by creating that record, you're
requesting TLS reports about your MX host.
gathering all the TLS/policy results is somewhat tricky. the tentacles go
throughout the code. the positive result is that the TLS/policy-related code
had to be cleaned up a bit. for example, the smtpclient TLS modes now reflect
reality better, with independent settings about whether PKIX and/or DANE
verification has to be done, and/or whether verification errors have to be
ignored (e.g. for tls-required: no header). also, cached mtasts policies of
mode "none" are now cleaned up once the MTA-STS DNS record goes away.
in smtpserver, we store dmarc evaluations (under the right conditions).
in dmarcdb, we periodically (hourly) send dmarc reports if there are
evaluations. for failed deliveries, we deliver the dsn quietly to a submailbox
of the postmaster mailbox.
this is on by default, but can be disabled in mox.conf.
getting mox to compile required changing code in only a few places where
package "syscall" was used: for accessing file access times and for umask
handling. an open problem is how to start a process as an unprivileged user on
windows. that's why "mox serve" isn't implemented yet. and just finding a way
to implement it now may not be good enough in the near future: we may want to
starting using a more complete privilege separation approach, with a process
handling sensitive tasks (handling private keys, authentication), where we may
want to pass file descriptors between processes. how would that work on
windows?
anyway, getting mox to compile for windows doesn't mean it works properly on
windows. the largest issue: mox would normally open a file, rename or remove
it, and finally close it. this happens during message delivery. that doesn't
work on windows, the rename/remove would fail because the file is still open.
so this commit swaps many "remove" and "close" calls. renames are a longer
story: message delivery had two ways to deliver: with "consuming" the
(temporary) message file (which would rename it to its final destination), and
without consuming (by hardlinking the file, falling back to copying). the last
delivery to a recipient of a message (and the only one in the common case of a
single recipient) would consume the message, and the earlier recipients would
not. during delivery, the already open message file was used, to parse the
message. we still want to use that open message file, and the caller now stays
responsible for closing it, but we no longer try to rename (consume) the file.
we always hardlink (or copy) during delivery (this works on windows), and the
caller is responsible for closing and removing (in that order) the original
temporary file. this does cost one syscall more. but it makes the delivery code
(responsibilities) a bit simpler.
there is one more obvious issue: the file system path separator. mox already
used the "filepath" package to join paths in many places, but not everywhere.
and it still used strings with slashes for local file access. with this commit,
the code now uses filepath.FromSlash for path strings with slashes, uses
"filepath" in a few more places where it previously didn't. also switches from
"filepath" to regular "path" package when handling mailbox names in a few
places, because those always use forward slashes, regardless of local file
system conventions. windows can handle forward slashes when opening files, so
test code that passes path strings with forward slashes straight to go stdlib
file i/o functions are left unchanged to reduce code churn. the regular
non-test code, or test code that uses path strings in places other than
standard i/o functions, does have the paths converted for consistent paths
(otherwise we would end up with paths with mixed forward/backward slashes in
log messages).
windows cannot dup a listening socket. for "mox localserve", it isn't
important, and we can work around the issue. the current approach for "mox
serve" (forking a process and passing file descriptors of listening sockets on
"privileged" ports) won't work on windows. perhaps it isn't needed on windows,
and any user can listen on "privileged" ports? that would be welcome.
on windows, os.Open cannot open a directory, so we cannot call Sync on it after
message delivery. a cursory internet search indicates that directories cannot
be synced on windows. the story is probably much more nuanced than that, with
long deep technical details/discussions/disagreement/confusion, like on unix.
for "mox localserve" we can get away with making syncdir a no-op.
increase() and rate() don't seem to assume a previous value of 0 when a vector
gets a first value for a label. you would think that an increase() on a
first-value mox_panic_total{"..."}=1 would return 1, and similar for rate(), but
that doesn't appear to be the behaviour. so we just explicitly initialize the
count to 0 for each possible label value. mox has more vector metrics, but
panics feels like the most important, and it's too much code to initialize them
all, for all combinations of label values. there is probably a better way that
fixes this for all cases...
at least the android gmail/mail app doesn't show messages without content-type
header. i believe missing content-type is meant to be interpreted as
text/plain, but doesn't hurt to be explicit.
for conditional storing and quick resynchronisation (not sure if mail clients are actually using it that).
each message now has a "modseq". it is increased for each change. with
condstore, imap clients can request changes since a certain modseq. that
already allows quickly finding changes since a previous connection. condstore
also allows storing (e.g. setting new message flags) only when the modseq of a
message hasn't changed.
qresync should make it fast for clients to get a full list of changed messages
for a mailbox, including removals.
we now also keep basic metadata of messages that have been removed (expunged).
just enough (uid, modseq) to tell client that the messages have been removed.
this does mean we have to be careful when querying messages from the database.
we must now often filter the expunged messages out.
we also keep "createseq", the modseq when a message was created. this will be
useful for the jmap implementation.
the default transport is still just "direct delivery", where we connect to the
destination domain's MX servers.
other transports are:
- regular smtp without authentication, this is relaying to a smarthost.
- submission with authentication, e.g. to a third party email sending service.
- direct delivery, but with with connections going through a socks proxy. this
can be helpful if your ip is blocked, you need to get email out, and you have
another IP that isn't blocked.
keep in mind that for all of the above, appropriate SPF/DKIM settings have to
be configured. the "dnscheck" for a domain does a check for any SOCKS IP in the
SPF record. SPF for smtp/submission (ranges? includes?) and any DKIM
requirements cannot really be checked.
which transport is used can be configured through routes. routes can be set on
an account, a domain, or globally. the routes are evaluated in that order, with
the first match selecting the transport. these routes are evaluated for each
delivery attempt. common selection criteria are recipient domain and sender
domain, but also which delivery attempt this is. you could configured mox to
attempt sending through a 3rd party from the 4th attempt onwards.
routes and transports are optional. if no route matches, or an empty/zero
transport is selected, normal direct delivery is done.
we could already "submit" emails with 3rd party accounts with "sendmail". but
we now support more SASL authentication mechanisms with SMTP (not only PLAIN,
but also SCRAM-SHA-256, SCRAM-SHA-1 and CRAM-MD5), which sendmail now also
supports. sendmail will use the most secure mechanism supported by the server,
or the explicitly configured mechanism.
for issue #36 by dmikushin. also based on earlier discussion on hackernews.
makes it easier to use tls keys/certs managed by other tools, with or without
acme. the root process has access to open such files. the child process reads
the key from the file descriptor, then closes the file.
for issue #30 by inigoserna, thanks!
the backup command will make consistent snapshots of all the database files. i
had been copying the db files before, and it usually works. but if the file is
modified during the backup, it is inconsistent and is likely to generate errors
when reading (can be at any moment in the future, when reading some db page).
"mox backup" opens the database file and writes out a copy in a transaction.
it also duplicates the message files.
before doing a restore, you could run "mox verifydata" on the to-be-restored
"data" directory. it check the database files, and compares the message files
with the database.
the new "gentestdata" subcommand generates a basic "data" directory, with a
queue and a few accounts. we will use it in the future along with "verifydata"
to test upgrades from old version to the latest version. both when going to the
next version, and when skipping several versions. the script test-upgrades.sh
executes these tests and doesn't do anything at the moment, because no releases
have this subcommand yet.
inspired by a failed upgrade attempt of a pre-release version.
localserve creates a config for listening on localhost for
imap/smtp/submission/http, on port numbers 1000 + the common service port
numbers. all incoming email is accepted (if checks pass), and a few pattern in
localparts are recognized and result in delivery errors.
the idea is to make it clear from the logging if non-ascii characters are used.
this is implemented by making mlog recognize if a field value that will be
logged has a LogString method. if so, that value is logged. dns.Domain,
smtp.Address, smtp.Localpart, smtp.Path now have a LogString method.
some explicit calls to String have been replaced to LogString, and some %q
formatting have been replaced with %s, because the escaped localpart would
already have double quotes, and double doublequotes aren't easy to read.
- serve static files, serving index.html or optionally listings for directories
- redirects
- reverse-proxy, forwarding requests to a backend
these are configurable through the config file. a domain and path regexp have to
be configured. path prefixes can be stripped. configured domains are added to
the autotls allowlist, so acme automatically fetches certificates for them.
all webserver requests now have (access) logging, metrics, rate limiting.
on http errors, the error message prints an encrypted cid for relating with log files.
this also adds a new mechanism for example config files.
makes it easier to run on bsd's, where you cannot (easily?) let non-root users
bind to ports <1024. starting as root also paves the way for future improvements
with privilege separation.
unfortunately, this requires changes to how you start mox. though mox will help
by automatically fix up dir/file permissions/ownership.
if you start mox from the systemd unit file, you should update it so it starts
as root and adds a few additional capabilities:
# first update the mox binary, then, as root:
./mox config printservice >mox.service
systemctl daemon-reload
systemctl restart mox
journalctl -f -u mox &
# you should see mox start up, with messages about fixing permissions on dirs/files.
if you used the recommended config/ and data/ directory, in a directory just for
mox, and with the mox user called "mox", this should be enough.
if you don't want mox to modify dir/file permissions, set "NoFixPermissions:
true" in mox.conf.
if you named the mox user something else than mox, e.g. "_mox", add "User: _mox"
to mox.conf.
if you created a shared service user as originally suggested, you may want to
get rid of that as it is no longer useful and may get in the way. e.g. if you
had /home/service/mox with a "service" user, that service user can no longer
access any files: only mox and root can.
this also adds scripts for building mox docker images for alpine-supported
platforms.
the "restart" subcommand has been removed. it wasn't all that useful and got in
the way.
and another change: when adding a domain while mtasts isn't enabled, don't add
the per-domain mtasts config, as it would cause failure to add the domain.
based on report from setting up mox on openbsd from mteege.
and based on issue #3. thanks for the feedback!
so users can easily take their email out of somewhere else, and import it into mox.
this goes a little way to give feedback as the import progresses: upload
progress is shown (surprisingly, browsers aren't doing this...), imported
mailboxes/messages are counted (batched) and import issues/warnings are
displayed, all sent over an SSE connection. an import token is stored in
sessionstorage. if you reload the page (e.g. after a connection error), the
browser will reconnect to the running import and show its progress again. and
you can just abort the import before it is finished and committed, and nothing
will have changed.
this also imports flags/keywords from mbox files.
