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.
needed for upcoming changes, where (now) package admin needs to import package
store. before, because package store imports mox- (for accessing the active
config), that would lead to a cyclic import. package mox- keeps its active
config, package admin has the higher-level config-changing functions.
if files {webmail,webaccount,webadmin}.{css,js} exist in the configdir (where
the mox.conf file lives), their contents are included in the web apps.
the webmail now uses css variables, mostly for colors. so you can write a
custom webmail.css that changes the variables, e.g.:
:root {
--color: blue
}
you can also look at css class names and override their styles.
in the future, we may want to make some css variables configurable in the
per-user settings in the webmail. should reduce the number of variables first.
any custom javascript is loaded first. if it defines a global function
"moxBeforeDisplay", that is called each time a page loads (after
authentication) with the DOM element of the page content as parameter. the
webmail is a single persistent page. this can be used to make some changes to
the DOM, e.g. inserting some elements. we'll have to see how well this works in
practice. perhaps some patterns emerge (e.g. adding a logo), and we can make
those use-cases easier to achieve.
helps partially with issue #114, and based on questions from laura-lilly on
matrix.
if admin has disabled mta-sts for a domain, we still check for records &
policies, but won't mark it as error when they don't exist. we do now keep
warning that mta-sts isn't enabled, otherwise we would start showing a green
"ok".
this also fixes the mta-sts code returning ErrNoPolicy when mtasts.<domain>
doesn't exist. the dns lookup is done with the reguler "net" package dns lookup
code, not through adns, so we look for two types of DNSError's.
noticed a while ago when testing with MTA-STS while debugging TLS connection
issues with MS.
before, the suggested records would show "v=spf1 mx ~all", while the dnscheck
page would suggest "v=spf1 ip4:... ip6:... -all".
the two places now show the same record: explicitly listing the configured ip's
(so the common case of a valid message is fast and doesn't require lookups of
mx hosts and their addresses), but still including "mx" (may prevent issues
while migrating to new ips in the future and doesn't hurt for legit messages),
and "~all" (for compatibility with some old systems that don't look at
dkim/dmarc when they evaluate spf and reach "-all")
based on #176 created by rdelaage, with record mismatch spotted by RobSlgm,
thanks!
if no host keys are configured, show as warning (yellow) that dane isn't
configured, and show instructions to enable it.
for issue #185 by morki, thanks for reporting!
the suggested dns records mention that these records are optional, but the
dnscheck makes it look serious. not helpful.
also remove unneeded whitespace in list of errors/warnings.
for issue #184 by morki, thanks for reporting!
the host tlsrpt record implied it was for the domain, but should have been for
the mail host.
some dns records were absolute, others weren't. now they all are for
consistency.
for issue #182 by mdavids, thanks for reporting!
per listener, you could enable the admin/account/webmail/webapi handlers. but
that would serve those services on their configured paths (/admin/, /,
/webmail/, /webapi/) on all domains mox would be webserving, including any
non-mail domains. so your www.example/admin/ would be serving the admin web
interface, with no way to disabled that.
with this change, the admin interface is only served on requests to (based on
Host header):
- ip addresses
- the listener host name (explicitly configured in the listener, with fallback
to global hostname)
- "localhost" (for ssh tunnel/forwarding scenario's)
the account/webmail/webapi interfaces are served on the same domains as the
admin interface, and additionally:
- the client settings domains, as optionally configured in each Domain in
domains.conf. typically "mail.<yourdomain>".
this means the internal services are no longer served on other domains
configured in the webserver, e.g. www.example.org/admin/ will not be handled
specially.
the order of evaluation of routes/services is also changed:
before this change, the internal handlers would always be evaluated first.
with this change, only the system handlers for
MTA-STS/autoconfig/ACME-validation will be evaluated first. then the webserver
handlers. and finally the internal services (admin/account/webmail/webapi).
this allows an admin to configure overrides for some of the domains (per
hostname-matching rules explained above) that would normally serve these
services.
webserver handlers can now be configured that pass the request to an internal
service: in addition to the existing static/redirect/forward config options,
there is now an "internal" config option, naming the service
(admin/account/webmail/webapi) for handling the request. this allows enabling
the internal services on custom domains.
for issue #160 by TragicLifeHu, thanks for reporting!
the members must currently all be addresses of local accounts.
a message sent to an alias is accepted if at least one of the members accepts
it. if no members accepts it (e.g. due to bad reputation of sender), the
message is rejected.
if a message is submitted to both an alias addresses and to recipients that are
members of the alias in an smtp transaction, the message will be delivered to
such members only once. the same applies if the address in the message
from-header is the address of a member: that member won't receive the message
(they sent it). this prevents duplicate messages.
aliases have three configuration options:
- PostPublic: whether anyone can send through the alias, or only members.
members-only lists can be useful inside organizations for internal
communication. public lists can be useful for support addresses.
- ListMembers: whether members can see the addresses of other members. this can
be seen in the account web interface. in the future, we could export this in
other ways, so clients can expand the list.
- AllowMsgFrom: whether messages can be sent through the alias with the alias
address used in the message from-header. the webmail knows it can use that
address, and will use it as from-address when replying to a message sent to
that address.
ideas for the future:
- allow external addresses as members. still with some restrictions, such as
requiring a valid dkim-signature so delivery has a chance to succeed. will
also need configuration of an admin that can receive any bounces.
- allow specifying specific members who can sent through the list (instead of
all members).
for github issue #57 by hmfaysal.
also relevant for #99 by naturalethic.
thanks to damir & marin from sartura for discussing requirements/features.
the stuttering was introduced to make the same type name declared in multiple
packages, and used in the admin sherpa api, unique. with sherpadoc's new
rename, we can make them unique when generating the api definition/docs, and
the Go code can use nicer names.
for dmarc reporting address, tls reporting address, mtasts policy, dkim keys/selectors.
should make it easier for webadmin-using admins to discover these settings.
the webadmin interface is now on par with functionality you would set through
the configuration file, let's keep it that way.
this simplifies some of the code that makes modifications to the config file. a
few protected functions can make changes to the dynamic config, which webadmin
can use. instead of having separate functions in mox-/admin.go for each type of
change.
this also exports the parsed full dynamic config to webadmin, so we need fewer
functions for specific config fields too.
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
typescript now knows the full types, not just "any" for account config.
inline structs previously in config.Account are given their own type definition
so sherpa can generate types.
also update to latest sherpa lib that knows about time.Duration, to be used soon.
- 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.
we only have a "storage" limit. for total disk usage. we don't have a limit on
messages (count) or mailboxes (count). also not on total annotation size, but
we don't have support annotations at all at the moment.
we don't implement setquota. with rfc 9208 that's allowed. with the previous
quota rfc 2087 it wasn't.
the status command can now return "DELETED-STORAGE". which should be the disk
space that can be reclaimed by removing messages with the \Deleted flags.
however, it's not very likely clients set the \Deleted flag without expunging
the message immediately. we don't want to go through all messages to calculate
the sum of message sizes with the deleted flag. we also don't currently track
that in MailboxCount. so we just respond with "0". not compliant, but let's
wait until someone complains.
when returning quota information, it is not possible to give the current usage
when no limit is configured. clients implementing rfc 9208 should probably
conclude from the presence of QUOTA=RES-* capabilities (only in rfc 9208, not
in 2087) and the absence of those limits in quota responses (or the absence of
an untagged quota response at all) that a resource type doesn't have a limit.
thunderbird will claim there is no quota information when no limit was
configured, so we can probably conclude that it implements rfc 2087, but not
rfc 9208.
we now also show the usage & limit on the account page.
for issue #115 by pmarini
both when parsing our configs, and for incoming on smtp or in messages.
so we properly compare things like é and e+accent as equal, and accept the
different encodings of that same address.
by mentioning the dnssec root keys, mentioning which unbound version has EDE,
giving a "dig" invocation to check for dnssec results.
based on issue #131 by romner-set, thanks for reporting
check the authentic data bit for the NS records of "com.", not for ".": some
dnssec-verifying resolvers return unauthentic data for ".".
for issue #139 by triatic, thanks!
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.
the http basic auth we had was very simple to reason about, and to implement.
but it has a major downside:
there is no way to logout, browsers keep sending credentials. ideally, browsers
themselves would show a button to stop sending credentials.
a related downside: the http auth mechanism doesn't indicate for which server
paths the credentials are.
another downside: the original password is sent to the server with each
request. though sending original passwords to web servers seems to be
considered normal.
our new approach uses session cookies, along with csrf values when we can. the
sessions are server-side managed, automatically extended on each use. this
makes it easy to invalidate sessions and keeps the frontend simpler (than with
long- vs short-term sessions and refreshing). the cookies are httponly,
samesite=strict, scoped to the path of the web interface. cookies are set
"secure" when set over https. the cookie is set by a successful call to Login.
a call to Logout invalidates a session. changing a password invalidates all
sessions for a user, but keeps the session with which the password was changed
alive. the csrf value is also random, and associated with the session cookie.
the csrf must be sent as header for api calls, or as parameter for direct form
posts (where we cannot set a custom header). rest-like calls made directly by
the browser, e.g. for images, don't have a csrf protection. the csrf value is
returned by the Login api call and stored in localstorage.
api calls without credentials return code "user:noAuth", and with bad
credentials return "user:badAuth". the api client recognizes this and triggers
a login. after a login, all auth-failed api calls are automatically retried.
only for "user:badAuth" is an error message displayed in the login form (e.g.
session expired).
in an ideal world, browsers would take care of most session management. a
server would indicate authentication is needed (like http basic auth), and the
browsers uses trusted ui to request credentials for the server & path. the
browser could use safer mechanism than sending original passwords to the
server, such as scram, along with a standard way to create sessions. for now,
web developers have to do authentication themselves: from showing the login
prompt, ensuring the right session/csrf cookies/localstorage/headers/etc are
sent with each request.
webauthn is a newer way to do authentication, perhaps we'll implement it in the
future. though hardware tokens aren't an attractive option for many users, and
it may be overkill as long as we still do old-fashioned authentication in smtp
& imap where passwords can be sent to the server.
for issue #58
all ui frontend code is now in typescript. we no longer need jshint, and we
build the frontend code during "make build".
this also changes tlsrpt types for a Report, not encoding field names with
dashes, but to keep them valid identifiers in javascript. this makes it more
conveniently to work with in the frontend, and works around a sherpats
limitation.
the autoconfig/autodiscover endpoints, and the printed client settings (in
quickstart, in the admin interface) now all point to the cname record (called
"client settings domain"). it is configurable per domain, and set to
"mail.<domain>" by default. for existing mox installs, the domain can be added
by editing the config file.
this makes it easier for a domain to migrate to another server in the future.
client settings don't have to be updated, the cname can just be changed.
before, the hostname of the mail server was configured in email clients.
migrating away would require changing settings in all clients.
if a client settings domain is configured, a TLS certificate for the name will
be requested through ACME, or must be configured manually.
should prevent potential mitm attacks. especially when done close to the
machine itself (where a http/tls challenge is intercepted to get a valid
certificate), as seen on the internet last month.
so a single user cannot fill up the disk.
by default, there is (still) no limit. a default can be set in the config file
for all accounts, and a per-account max size can be set that would override any
global setting.
this does not take into account disk usage of the index database. and also not
of any file system overhead.
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.
based on discussion on uta mailing list. it seems the intention of the tlsrpt
is to only send reports to recipient domains. but i was able to interpret the
tlsrpt rfc as sending reports to mx hosts too ("policy domain", and because it
makes sense given how DANE works per MX host, not recipient domain). this
change makes the behaviour of outgoing reports to recipient domains work more
in line with expectations most folks may have about tls reporting (i.e. also
include per-mx host tlsa policies in the report). this also keeps reports to mx
hosts working, and makes them more useful by including the recipient domains of
affected deliveries.
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.
instead of requiring policy domains to be configured recipient domains.
when accessing TLS reports, always do it under path #tlsrpt/reports, not under #domain/.../tlsrpt.
- accept incoming tls reports for the host, with policy-domain the host name.
instead of not storing the domain because it is not a configured (recipient)
domain.
- in tlsrpt summaries, rename domain to policy domain for clarity.
- in webadmin, fix html for table that lists tls reports in case of multiple
policies and/or multiple failure details.
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.
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".
because the txt would already follow cnames.
the additional cname lookup didn't hurt, it just didn't do anything.
i probably didn't realize that before looking deeper into dns.
people will either paste the records in their zone file. in that case, the
records will inherit "IN" from earlier records, and there will always be one
record. if anyone uses a different class, their smart enough to know they need
to add IN manually.
plenty of people will add their records through some clunky web interface of
their dns operator. they probably won't even have the choice to set the class,
it'll always be IN.
the vendored dns resolver code is a copy of the go stdlib dns resolver, with
awareness of the "authentic data" (i.e. dnssec secure) added, as well as support
for enhanced dns errors, and looking up tlsa records (for dane). ideally it
would be upstreamed, but the chances seem slim.
dnssec-awareness is added to all packages, e.g. spf, dkim, dmarc, iprev. their
dnssec status is added to the Received message headers for incoming email.
but the main reason to add dnssec was for implementing dane. with dane, the
verification of tls certificates can be done through certificates/public keys
published in dns (in the tlsa records). this only makes sense (is trustworthy)
if those dns records can be verified to be authentic.
mox now applies dane to delivering messages over smtp. mox already implemented
mta-sts for webpki/pkix-verification of certificates against the (large) pool
of CA's, and still enforces those policies when present. but it now also checks
for dane records, and will verify those if present. if dane and mta-sts are
both absent, the regular opportunistic tls with starttls is still done. and the
fallback to plaintext is also still done.
mox also makes it easy to setup dane for incoming deliveries, so other servers
can deliver with dane tls certificate verification. the quickstart now
generates private keys that are used when requesting certificates with acme.
the private keys are pre-generated because they must be static and known during
setup, because their public keys must be published in tlsa records in dns.
autocert would generate private keys on its own, so had to be forked to add the
option to provide the private key when requesting a new certificate. hopefully
upstream will accept the change and we can drop the fork.
with this change, using the quickstart to setup a new mox instance, the checks
at internet.nl result in a 100% score, provided the domain is dnssec-signed and
the network doesn't have any issues.
