the field is optional. if absent, the default behaviour is currently to disable
session tickets. users can set the option if they want to try if delivery from
microsoft is working again. in a future version, we can switch the default to
enabling session tickets.
the previous fix was to disable session tickets for all tls connections,
including https. that was a bit much.
for issue #237
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.
instead of failing the connection because no certificates are available.
this may improve interoperability. perhaps the remote smtp client that's doing
the delivery will decide they do like the tls cert for our (mx) hostname after
all.
this only applies to incoming smtp deliveries. for other tls connections
(https, imaps/submissions and imap/submission with starttls) we still cause
connections for unknown sni hostnames to fail. if case no sni was present, we
were already falling back to a cert for the (listener/mx) hostname, that
behaviour hasn't changed.
for issue #206 by RobSlgm
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.
if the message has a list-id header, we assume this is a (mailing) list
message, and we require a dkim/spf-verified domain (we prefer the shortest that
is a suffix of the list-id value). the rule we would add will mark such
messages as from a mailing list, changing filtering rules on incoming messages
(not enforcing dmarc policies). messages will be matched on list-id header and
will only match if they have the same dkim/spf-verified domain.
if the message doesn't have a list-id header, we'll ask to match based on
"message from" address.
we don't ask the user in several cases:
- if the destination/source mailbox is a special-use mailbox (e.g.
trash,archive,sent,junk; inbox isn't included)
- if the rule already exist (no point in adding it again).
- if the user said "no, not for this list-id/from-address" in the past.
- if the user said "no, not for messages moved to this mailbox" in the past.
we'll add the rule if the message was moved out of the inbox.
if the message was moved to the inbox, we check if there is a matching rule
that we can remove.
we now remember the "no" answers (for list-id, msg-from-addr and mailbox) in
the account database.
to implement the msgfrom rules, this adds support to rulesets for matching on
message "from" address. before, we could match on smtp from address (and other
fields). rulesets now also have a field for comments. webmail adds a note that
it created the rule, with the date.
manual editing of the rulesets is still in the webaccount page. this webmail
functionality is just a convenient way to add/remove common rules.
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
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
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.
you can configure a domain only to accept dmarc/tls reports. those domains
won't have addresses for that domain configured (the reporting destination
address is for another domain). we already handled such domains specially in a
few places. but we were considering ourselves authoritative for such domains if
an smtp client would send a message to the domain during submit. and we would
reject all recipient addresses. but we should be trying to deliver those
messages to the actual mx hosts for the domain, which we will now do.
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.
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.
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.
- 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.
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.
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.
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.
to accept reports for another domain, first add that domain to the config,
leaving all options empty except DMARC/TLSRPT in which you configure a Domain.
the suggested DNS DMARC/TLSRPT records will show the email address with
configured domain. for DMARC, the dnscheck functionality will verify that the
destination domain has opted in to receiving reports.
there is a new command-line subcommand "mox dmarc checkreportaddrs" that
verifies if dmarc reporting destination addresses have opted in to received
reports.
this also changes the suggested dns records (in quickstart, and through admin
pages and cli subcommand) to take into account whether DMARC and TLSRPT is
configured, and with which localpart/domain (previously it always printed
records as if reporting was enabled for the domain). and when generating the
suggested DNS records, the dmarc.Record and tlsrpt.Record code is used, with
proper uri-escaping.
NATIPs lists the public IPs, so we can still do the DNS checks on them. with
IPsNATed, we disabled the checks.
based on feedback by kikoreis in issue #52
this is based on @bobobo1618's PR #50. bobobo1618 had the right idea, i tried
including an "is forwarded email" configuration option but that indeed became
too tightly coupled. the "is forwarded" option is still planned, but it is
separate from the "accept rejects to mailbox" config option, because one could
still want to push back on forwarded spam messages.
we do an actual accept, delivering to a configured mailbox, instead of storing
to the rejects mailbox where messages can automatically be removed from. one
of the goals of mox is not pretend to accept email while actually junking it.
users can still configure delivery to a junk folder (as was already possible),
but aren't deleted automatically. there is still an X-Mox-Reason header in the
message, and a log line about accepting the reject, but otherwise it is
registered and treated as an (smtp) accept.
the ruleset mailbox is still required to keep that explicit. users can specify
Inbox again.
hope this is good enough for PR #50, otherwise we'll change it.
a few places still looked at the name "Sent". but since we have special-use
flags, we should always look at those. this also changes the config so admins
can specify different names for the special-use mailboxes to create for new
accounts, e.g. in a different language. the old config option is still
understood, just deprecated.
it's still not great. better to automatically change domains.conf. but that
would currently rewrite the whole file, which may not be what admins that
manually edit expect, it would remove their comments. we need better
config-update code.
for issue #40
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!
by specifying a "destination" in an account that is just "@" followed by the
domain, e.g. "@example.org". messages are only delivered to the catchall
address when no regular destination matches (taking the per-domain
catchall-separator and case-sensisitivity into account).
for issue #18
such configurations are certainly errors, but were silently accepted and highly
likely not doing what you may have hoped. i suspect no one has configured mox
this way.
so you can use the host (domain) name of the mail server for serving other
resources too. the default is is still that account is served on /, and so
takes all incoming requests before giving webhandlers a chance.
mox localserve now serves the account pages on /account/
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.
current behaviour isn't intuitive. it's not great to have to attempt parsing
the strings as both localpart and email address. so we deprecate the
localpart-only behaviour. when we load the config file, and it has
localpart-only Destinations keys, we'll change them to full addresses in
memory. when an admin causes a write of domains.conf, it'll automatically be
fixed. we log an error with a deprecated notice for each localpart-only
destinations key.
sometime in the future, we can remove the old localpart-only destination
support. will be in the release notes then.
also start keeping track of update notes that need to make it in the release
notes of the next release.
for issue #18
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.
