See https://meta.discourse.org/t/discourse-email-messages-are-incorrectly-threaded/233499
for thorough reasoning.
This commit changes how we generate Message-IDs and do email
threading for emails sent from Discourse. The main changes are
as follows:
* Introduce an outbound_message_id column on Post that
is either a) filled with a Discourse-generated Message-ID
the first time that post is used for an outbound email
or b) filled with an original Message-ID from an external
mail client or service if the post was created from an
incoming email.
* Change Discourse-generated Message-IDs to be more consistent
and static, in the format `discourse/post/:post_id@:host`
* Do not send References or In-Reply-To headers for emails sent
for the OP of topics.
* Make sure that In-Reply-To is filled with either a) the OP's
Message-ID if the post is not a direct reply or b) the parent
post's Message-ID
* Make sure that In-Reply-To has all referenced post's Message-IDs
* Make sure that References is filled with a chain of Message-IDs
from the OP down to the parent post of the new post.
We also are keeping X-Discourse-Post-Id and X-Discourse-Topic-Id,
headers that we previously removed, for easier visual debugging
of outbound emails.
Finally, we backfill the `outbound_message_id` for posts that have
a linked `IncomingEmail` record, using the `message_id` of that record.
We do not need to do that for posts that don't have an incoming email
since they are backfilled at runtime if `outbound_message_id` is missing.
The maximum_staged_users_per_email site setting controls how many
staged users will be invited to the topic created from an incoming
email. Previously, it counted only the new staged users.
Mozilla Thunderbird email client add links into HTML as follows:
`<p>The link: <a class="moz-txt-link-freetext" href="https://google.com">https://google.com</a></p>`
Current filtering rules strip out the link, leaving only `<p>The link: </p>`.
Properly strip only unnecessary information: quote prefix, signature, forwarded message header.
This allows text editors to use correct syntax coloring for the heredoc sections.
Heredoc tag names we use:
languages: SQL, JS, RUBY, LUA, HTML, CSS, SCSS, SH, HBS, XML, YAML/YML, MF, ICS
other: MD, TEXT/TXT, RAW, EMAIL
Whenever we got a bounced email in the Email::Receiver we
previously would just set bounced: true on the EmailLog and
discard the status/diagnostic code. This commit changes this
flow to store the bounce error code (defined in the RFC at
https://www.iana.org/assignments/smtp-enhanced-status-codes/smtp-enhanced-status-codes.xhtml)
not just in the Email::Receiver, but also via webhook events
from other mail services and from SNS.
This commit does not surface the bounce error in the UI,
we can do that later if necessary.
Currently the Message-IDs we send out for outbound email
are not unique; for a post they look like:
topic/TOPIC_ID/POST_ID@HOST
And for a topic they look like:
topic/TOPIC_ID@HOST
This commit changes the outbound Message-IDs to also have
a random suffix before the host, so the new format is
like this:
topic/TOPIC_ID/POST_ID.RANDOM_SUFFIX@HOST
Or:
topic/TOPIC_ID.RANDOM_SUFFIX@HOST
This should help with email deliverability. This change
is backwards-compatible, the old Message-ID format will
still be recognized in the mail receiver flow, so people
will still be able to reply using Message-IDs, In-Reply-To,
and References headers that have already been sent.
This commit also refactors Message-ID related logic
to a central location, and adds judicious amounts of
tests and documentation.
Usually, when an email is received a user lookup is performed using the
email address found in the `From` header. When an email has an
`X-Original-From` header, if it is equal to `Reply-To` then it uses that
one instead. The comparison was sensitive to whitespaces and other
insignificant characters such as quotes because it reconstructed the
`From` header.
For the fixture added in this commit, it compared the reconstructed
`From` header `John Doe <johndoe@example.com>` with the `Reply-To`
header `"John Doe" <johndoe@example.com>`.
The display name can have quotes around it, which does not work
with our current comparison of a from field (in this case Reply-To)
and another header (X-Original-From), because we are not comparing
the two values in the same way. This causes an issue where the
commit here: b88d8c8 will not
work properly; the forwarded email gets the From address instead
of the Reply-To address as intended.
When forwarding emails into the group inbox, we now use the
original sender email as the from_address since
2ac9fd9dff. However, we have not
been saving the original CC addresses of the forwarded email,
which are needed to include those recipients in on the conversation
when replying via the group inbox.
This commit captures the CC addresses on the incoming email, and
makes sure the emails are created as staged users and added to the
list of topic allowed users so they are included on CC's sent by
the GroupSmtpEmail and other jobs.
When 2ac9fd9dff was done, this
affected the small post that is created when forwarding an email
into the group inbox. Instead of using the name and the email of
the user who forwarded the email, it used the original from email
and name to create the small post. So instead of something like
"Discourse Team forwarded the above email" we ended up with
"John Smith forwarded the above email" which is incorrect.
This fixes the issue by creating a staged user for the forwarding
email address (if such a user does not yet exist) and uses that
for the "forwarded" small post instead.
When emails were forwarded to a group inbox by the email address
of the group, for example when an email ends up in spam and must
be manually forwarded to the group+site@discoursemail.com address,
the OP of the topic ended up being the group's email address instead
of the sender who originally sent the email to the group inbox.
This commit detects that an email has been forwarded using existing
tools, and if the from address matches one of the group incoming
email addresses, then we look at the forwarded email's from address
and use that instead for the incoming email from address as well as
the staged/regular user used for the Topic.user.
This will make it much cleaner to forward emails into a group inbox,
and will prevent issues with PostAlerter where the OP is double-notified
for these emails.
Emails can include the marker in a different language, depending on
site and user settings. The email receiver always looked for the marker
in default language.
The following example message would generate an exception:
```
Return-Path: <discourse@bar.com>
From: Foo Bar <discourse@bar.com>
To: reply+4f97315cc828096c9cb34c6f1a0d6fe8@bar.com
Date: Fri, 15 Jan 2016 00:12:43 +0100
Message-ID: <21@foo.bar.mail>
Mime-Version: 1.0
Content-Type: text/html; charset=UTF-8
</div>
```
Exception:
```
NoMethodError:
undefined method `split' for nil:NilClass
```
When the Reply-To header is present for incoming emails we
want to use it instead of the from address. This is usually the
case when forwarding an email via a mailing list into Discourse.
For now we are only using the Reply-To header if the email has
been forwarded via Google Groups, which is why we are checking the
X-Original-From header too. In future we may want to use the Reply-To
header in more cases.
We already reject email replies to public topics via `SiteSetting.disallow_reply_by_email_after_days` and raising the `OldDestinationError`. This PR introduces similar behaviour for group inboxes, but without the rejection, and **only when SMTP is enabled for the group**.
If a reply is sent via email and the post is older than `SiteSetting.disallow_reply_by_email_after_days` days ago, then we create a new topic instead of making a reply in the old one and link back to the original topic. This is done to prevent long running group inbox discussions.
When replying to a user_private_message email originating from
a group PM that does _not_ have a reply key (e.g. when replying
directly to the group's SMTP address), we were mistakenly linking
the new post created from the reply to the OP and the user who
created the topic, based on the first IncomingEmail message ID in
the topic, rather than using the correct reply to user and post number
that the user actually replied to.
We now use the In-Reply-To header to look up the corresponding EmailLog
record when the user who replied was sent a user_private_message email,
and use the post from that as the reply_to_user/post.
This also removes superfluous filtering of incoming_email records. After
already filtering by message_id and then addressed_to_user (which only
returns incoming emails where the to, from, or cc address includes any
of the user's emails), we were filtering again but in the ruby code for
the exact same conditions. After removing this all existing tests still
pass.
This PR changes the `UserNotification` class to send outbound `user_private_message` using the group's SMTP settings, but only if:
* The first allowed_group on the topic has SMTP configured and enabled
* SiteSetting.enable_smtp is true
* The group does not have IMAP enabled, if this is enabled the `GroupSMTPMailer` handles things
The email is sent using the group's `email_username` as both the `from` and `reply-to` address, so when the user replies from their email it will go through the group's SMTP inbox, which needs to have email forwarding set up to send the message on to a location (such as a hosted site email address like meta@discoursemail.com) where it can be POSTed into discourse's handle_mail route.
Also includes a fix to `EmailReceiver#group_incoming_emails_regex` to include the `group.email_username` so the group does not get a staged user created and invited to the topic (which was a problem for IMAP), as well as updating `Group.find_by_email` to find using the `email_username` as well for inbound emails with that as the TO address.
#### Note
This is safe to merge without impacting anyone seriously. If people had SMTP enabled for a group they would have IMAP enabled too currently, and that is a very small amount of users because IMAP is an alpha product, and also because the UserNotification change has a guard to make sure it is not used if IMAP is enabled for the group. The existing IMAP tests work, and I tested this functionality by manually POSTing replies to the SMTP address into my local discourse.
There will probably be more work needed on this, but it needs to be tested further in a real hosted environment to continue.
This setting allows admin to de/activate automatic trimming of incoming email.
There are instances where it does wonders in trimming all the garbage content and other
instances where it's so bad that it trims the most important part of the email.
FIX: don't remove hidden content using the style attribute when converting HTML to Markdown.
The regexp used was doing more harm than good. It was way too broad.
FIX: properly elide signatures from emails sent with Front App.
This is fairly safe as Front App nicely identifies signatures in the HTML part.
Version 2.8 brings some changes to how address fields are handled and
this commits updates that and should also include a fix which handles
encoded attachment filenames.
The fork contains a bugfix to correctly decode mail attachments.
Adds a new column/setting to groups, allow_unknown_sender_topic_replies, which is default false. When enabled, this scenario is allowed via IMAP:
* OP sends an email to the support email address which is synced to a group inbox via IMAP, creating a group topic
* Group user replies to the group topic
* An email notification is sent to the OP of the topic via GroupSMTPMailer
* The OP has several email accounts and the reply is sent to all of them, or they forward their reply to another email account
* The OP replies from a different email address than the OP (gloria@gmail.com instead of gloria@hey.com for example)
* The a new staged user is created, the new reply is accepted and added to the topic, and the staged user is added to the topic allowed users
Without allow_unknown_sender_topic_replies enabled the new reply creates an entirely new topic (because the email address it is sent from is not previously part of the topic email chain).
This should make it easier to track down how the incoming email was created, which is one of four locations:
The POP3 poller (which picks up reply via email replies)
The admin email controller #handle_mail (which is where hosted mail is sent)
The IMAP sync tool
The group SMTP mailer, which sends emails when replying to IMAP topics, pre-emptively creating IncomingEmail records to avoid double syncing
This PR fixes a race condition with the IMAP notification code. In the `Email::Receiver` we call the `NewPostManager` to create the post and enqueue jobs and sends alerts via `PostAlerter`. However, if the post alerter reaches the `notify_pm_users` and the `group_notifying_via_smtp` method _before_ the incoming email is updated with the post and topic, we unnecessarily send a notification to the person who just posted. The result of this is that the IMAP syncer re-imports the email sent to the user about their own post, which looks like this in the group inbox:
To fix this, we skip the jobs enqueued by `NewPostManager` and only enqueue them with `PostJobsEnqueuer` manually _after_ the incoming email record has been updated with the post and topic.
Other improvements:
* Moved code to calculate email addresses from `IncomingEmail` records into the topic, with a group passed in, for easier testing and debugging. It is not the responsibility of the post alerter to figure this stuff out.
* Add shortcut methods on `IncomingEmail` to split or provide an empty array for to and cc addresses to avoid repetition.
Fixes a rare race condition causing the `Imap::Sync` class to create an incoming email and associated post/topic, which then kicks off the PostAlerter to notify others in the PM about a reply in the topic, but for the OP which is not necessary (because the person emailing the IMAP inbox already knows about the OP). Basically, we should never be sending the group SMTP email for the first post in a topic.
Also in this PR:
* Custom attribute accessors for the to/from/cc addresses on `IncomingEmail`, to parse them from an array to a joined string so the logic for this is only in one place.
* Store extra detail against the `IncomingEmail` created in `GroupSmtpMailer`
* regex test Mail header Reply-To as string instead of Field, which fixes `warning: deprecated Object#=~ is called on Mail::Field; it always returns nil`
* Add DEBUG_IMAP to log all IMAP logs as warnings for easier debugging
* Changed the Rails logging to `ImapSyncLog` in the `GroupSmtpMailer`
Adds functionality to reflect topic delete in Discourse to IMAP inbox (Gmail only for now) and reflecting Gmail deletes in Discourse.
Adding lots of tests, various refactors and code improvements.
When Discourse topic is destroyed in PostDestroyer mark the topic incoming email as imap_sync: true, and do the opposite when post is recovered.
Adds a imap_group_id column to IncomingEmail to deal with an issue where we were trying to update emails in the mailbox, calling IncomingEmail.where(imap_sync: true). However UID and UIDVALIDITY could be the same across accounts. So if group A used IMAP details for Gmail account A, and group B used IMAP details for Gmail account B, and both tried to sync changes to an email with UID of 3 (e.g. changing Labels), one account could affect the other. This even applied to Archiving!
Also in this PR:
* Fix error occurring if we do a uid_fetch and no emails are returned
* Allow for creating labels within the target mailbox (previously we would not do this, only use existing labels)
* Improve consistency for log messages
* Add specs for generic IMAP provider (Gmail specs still to come)
* Add custom archiving support for Gmail
* Only use Message-ID for uniqueness of IncomingEmail if it was generated by us
* Various refactors and improvements
* enqueue spam/dmarc failing emails instead of hiding
* add translations for dmarc/spam enqueued reasons
* unescape quote
* if email_in_authserv_id is blank return gray for all emails
We like to stay as close as possible to latest with rubocop cause the cops
get better.
This update required some code changes, specifically the default is to avoid
explicit returns where implicit is done
Also this renames a few rules
Martin Brennan
Bianca Nenciu
ValdikSS
Arpit Jalan
Jarek Radosz
Vinoth Kannan
David Taylor
Daniel Waterworth
Martin Brennan
Dan Ungureanu
Joffrey JAFFEUX
Régis Hanol
Gerhard Schlager
Krzysztof Kotlarek
Mark VanLandingham
Arpit Jalan
Leo McArdle
Sam Saffron