We normally recover from those situations, printing stack traces instead of
crashing the program. But during tests, we're not looking at the prometheus
metrics or all the output. Without these checks, such panics could go
unnoticed. Seems like a reasonable thing to add, unhandled panics haven't been
encountered in tests.
all relevant systems nowadays should be accepting "8-bit" messages. before this
change, we would fail delivery for 8bit messages when the remote server doesn't
announce the 8bitmime smtp extension. even though that system would likely
just accept our message.
also, there's a good chance the non-8bitmime-supporting system is some
intermediate minimal mail server like openbsd spamd, which was fixed to
announce the 8bitmime extension in the past year.
in theory, we could rewrite the message to be 7bit-only if it is a mime
message. but it's probably not worth the trouble. also see
https://cr.yp.to/smtp/8bitmime.html
as alternative to PR #287 by mattanja (who also reported the issue on matrix),
thanks!
to facilitate migrations from/to other mail setups.
a domain can be added in "disabled" mode (or can be disabled/enabled later on).
you can configure a disabled domain, but incoming/outgoing messages involving
the domain are rejected with temporary error codes (as this may occur during a
migration, remote servers will try again, hopefully to the correct machine or
after this machine has been configured correctly). also, no acme tls certs will
be requested for disabled domains (the autoconfig/mta-sts dns records may still
point to the current/previous machine). accounts with addresses at disabled
domains can still login, unless logins are disabled for their accounts.
an account now has an option to disable logins. you can specify an error
message to show. this will be shown in smtp, imap and the web interfaces. it
could contain a message about migrations, and possibly a URL to a page with
information about how to migrate. incoming/outgoing email involving accounts
with login disabled are still accepted/delivered as normal (unless the domain
involved in the messages is disabled too). account operations by the admin,
such as importing/exporting messages still works.
in the admin web interface, listings of domains/accounts show if they are disabled.
domains & accounts can be enabled/disabled through the config file, cli
commands and admin web interface.
for issue #175 by RobSlgm
the types in webhook should be subjected to apidiff'ing, this was a shared
function. it is better off in package queue. also change the apidiff script so
it leaves apidiff/next.txt empty when there aren't any changes. makes it easier
to rotate the files after releases where nothing changed (a common occurrence).
for each message part. The ContentDisposition value is the base value without
header key/value parameters. the Filename field is the likely filename of the
part. the different email clients encode filenames differently. there is a
standard mime mechanism from rfc 2231. and there is the q/b-word-encoding from
rfc 2047. instead of letting users of the webhook api deal with those
differences, we provide just the parsed filename.
for issue #258 by morki, thanks for reporting!
this allows removing some ugly instantiations of an rng based on the current
time.
Intn is now IntN for our concurrency-safe prng wrapper to match the randv2 api.
v2 exists since go1.22, which we already require.
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.
it's the responsibility of the sender to use unique fromid's.
we do check if that's the case, and return an error if not.
also make it more clear that "unique smtp mail from addresses" map to the
"FromIDLoginAddresses" account config field.
based on feedback from cuu508 for #31, thanks!
before, the smtpserver that queued a dsn would set an empty senderaccount,
which was interpreted in a few places as the globally configured postmaster
cacount. the empty senderaccount would be used by the smtpserver that queued a
dsn with null return path. we now set the postmaster account when we add a
message to the queue. more code in the queue pretty much needs a non-empty
senderaccount, such as the filters when listing, and the suppression list.
instead of skipping on any smtp and delivering messages to accounts.
we dial the ip of the smtp listener, which is localhost:1025 by default.
the smtp server now uses a mock dns resolver during spf & dkim verification for
hosted domains (localhost by default), so they should pass.
the advantage is that we get regular full smtp server behaviour for delivering
in localserve, including webhooks, and potential first-time sender delays
(though this is disabled by default now).
incoming deliveries now go through normal address resolution, where before we
would always deliver to mox@localhost. we still accept email for unknown
recipients to mox@localhost.
this will be useful upcoming alias/list functionality.
localserve will now generate a dkim key when creating a new config. existing
users may wish to reset (remove) their localserve directory, or add a dkim key.
time.Now() returns a timestamp with timezone Local. if you marshal & unmarshal
it again, it'll get the Local timezone again. unless the local timezone is UTC.
then it will get the UTC timezone. the same time.Time but with explicit UTC
timezone vs explicit UTC-as-Local timezone are not the same when comparing with
==. so comparison should be done with time.Time.Equal, or comparison should be
done after having called .Local() on parsed timestamps (so the explicit UTC
timezone gets converted to the UTC-as-Local timezone). somewhat surprising that
time.Local isn't the same as time.UTC if TZ=/TZ=UTC. there are warnings
throughout the time package about handling of UTC.
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
mox was already giving another try for received errors after the
`HELO`/`EHLO` command. Now mox do the same for received errors when
trying to deliver the message to the remote SMTP server.
This should help to deliver messages to SMTP server that rejects
incoming messages because of bad ipv4 or ipv6 configuration (for example
for servers checking reverse DNS records). mox will now try to deliver
messages on both ip family instead before considering the error as
permanent.
fix#149
The `TransportDirect` transport allows to tweak outgoing SMTP
connections to remote servers. Currently, it only allows to select
network IP family (ipv4, ipv6 or both).
For example, to disable ipv6 for all outgoing SMTP connections:
- add these lines in mox.conf to create a new transport named
"disableipv6":
```
Transports:
disableipv6:
Direct:
DisableIpv6: true
```
- then add these lines in domains.conf to use this transport:
```
Routes:
-
Transport: disableipv6
```
fix#149
- add option to put messages in the queue "on hold", preventing delivery
attempts until taken off hold again.
- add "hold rules", to automatically mark some/all submitted messages as "on
hold", e.g. from a specific account or to a specific domain.
- add operation to "fail" a message, causing a DSN to be delivered to the
sender. previously we could only drop a message from the queue.
- update admin page & add new cli tools for these operations, with new
filtering rules for selecting the messages to operate on. in the admin
interface, add filtering and checkboxes to select a set of messages to operate
on.
before, an error about an invalid address was not used, causing a delivery
attempt to an empty address (empty localpart/domain). delivery to that address
would fail, but we should've prevented that message from being queued at all.
additionally, an error in adding the message to the queue was ignored too.
transferring the data only once. we only do this when the recipient domains
are the same. when queuing, we now take care to set the same NextAttempt
timestamp, so queued messages are actually eligable for combined delivery.
this adds a DeliverMultiple to the smtp client. for pipelined requests, it will
send all RCPT TO (and MAIL and DATA) in one go, and handles the various
responses and error conditions, returning either an overal error, or per
recipient smtp responses. the results of the smtp LIMITS extension are also
available in the smtp client now.
this also takes the "LIMITS RCPTMAX" smtp extension into account: if the server
only accepts a single recipient, we won't send multiple.
if a server doesn't announce a RCPTMAX limit, but still has one (like mox does
for non-spf-verified transactions), we'll recognize code 452 and 552 (for
historic reasons) as temporary error, and try again in a separate transaction
immediately after. we don't yet implement "LIMITS MAILMAX", doesn't seem likely
in practice.
so you can still know when someone has put you on their blocklist (which may
affect delivery), without using them.
also query dnsbls for our ips more often when we do more outgoing connections
for delivery: once every 100 messages, but at least 5 mins and at most 3 hours
since the previous check.
have the full smtp reply in the Diagnostic-Code field, not something that
resembles it but isn't quite the same.
include any additional error message in the Status field as comment.
before, we ended up having an Diagnostic-Code that didn't include the original
smtp code. it only had the enhanced error code.
we now keep track of the full smtp error responses, potentially multi-line. and
we include it in a dsn in the first free-form human-readable text.
it can have multiple lines in practice, e.g. when a destination mail server
tries to be helpful in explaining what the problem is.
the smtp extension, rfc 4865.
also implement in the webmail.
the queueing/delivery part hardly required changes: we just set the first
delivery time in the future instead of immediately.
still have to find the first client that implements it.
to get the security benefits (detecting mitm attempts), explicitly configure
clients to use a scram plus variant, e.g. scram-sha-256-plus. unfortunately,
not many clients support it yet.
imapserver scram plus support seems to work with the latest imtest (imap test
client) from cyrus-sasl. no success yet with mutt (with gsasl) though.
- prometheus is now behind an interface, they aren't dependencies for the
reusable components anymore.
- some dependencies have been inverted: instead of packages importing a main
package to get configuration, the main package now sets configuration in
these packages. that means fewer internals are pulled in.
- some functions now have new parameters for values that were retrieved from
package "mox-".
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.
for reporting addresses that cause DSNs to be returned. that just adds noise.
the admin can add/remove/extend addresses through the webadmin.
in the future, we could send reports with a smtp mail from of
"postmaster+<signed-encoded-recipient>@...", and add the reporting recipient
on the suppression list automatically when a DSN comes in on that address, but
for now this will probably do.
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.
firstly by using crypto/rand in those cases. and secondly by putting a lock
around the Read (though it isn't used at the moment).
found while working while implementing sending tls reports.
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.
with requiretls, the tls verification mode/rules for email deliveries can be
changed by the sender/submitter. in two ways:
1. "requiretls" smtp extension to always enforce verified tls (with mta-sts or
dnssec+dane), along the entire delivery path until delivery into the final
destination mailbox (so entire transport is verified-tls-protected).
2. "tls-required: no" message header, to ignore any tls and tls verification
errors even if the recipient domain has a policy that requires tls verification
(mta-sts and/or dnssec+dane), allowing delivery of non-sensitive messages in
case of misconfiguration/interoperability issues (at least useful for sending
tls reports).
we enable requiretls by default (only when tls is active), for smtp and
submission. it can be disabled through the config.
for each delivery attempt, we now store (per recipient domain, in the account
of the sender) whether the smtp server supports starttls and requiretls. this
support is shown (after having sent a first message) in the webmail when
sending a message (the previous 3 bars under the address input field are now 5
bars, the first for starttls support, the last for requiretls support). when
all recipient domains for a message are known to implement requiretls,
requiretls is automatically selected for sending (instead of "default" tls
behaviour). users can also select the "fallback to insecure" to add the
"tls-required: no" header.
new metrics are added for insight into requiretls errors and (some, not yet
all) cases where tls-required-no ignored a tls/verification error.
the admin can change the requiretls status for messages in the queue. so with
default delivery attempts, when verified tls is required by failing, an admin
could potentially change the field to "tls-required: no"-behaviour.
messages received (over smtp) with the requiretls option, get a comment added
to their Received header line, just before "id", after "with".
the original next-hop domain. not anything after resolving cname's, because
then it takes just a single injected dns cname record to lead us to an
unrelated server (that we would verify, but it's the wrong server).
also don't fallback to just strict tls when something is wrong. we must use the
policy to check if an mx host is allowed. the whole idea is that unsigned dns
records cannot be trusted.
i noticed this while implementing dane.
