summaryrefslogtreecommitdiff
path: root/doc/administration/incoming_email.md
blob: 36156c4a5807b05e68915c70941601d2611a9947 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
---
stage: Plan
group: Project Management
info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
---

# Incoming email

GitLab has several features based on receiving incoming emails:

- [Reply by Email](reply_by_email.md): allow GitLab users to comment on issues
  and merge requests by replying to notification emails.
- [New issue by email](../user/project/issues/managing_issues.md#new-issue-via-email):
  allow GitLab users to create a new issue by sending an email to a
  user-specific email address.
- [New merge request by email](../user/project/merge_requests/creating_merge_requests.md#new-merge-request-by-email-core-only):
  allow GitLab users to create a new merge request by sending an email to a
  user-specific email address.
- [Service Desk](../user/project/service_desk.md): provide e-mail support to
  your customers through GitLab.

## Requirements

NOTE: **Note:**
It is **not** recommended to use an email address that receives or will receive any
messages not intended for the GitLab instance. Any incoming emails not intended
for GitLab will receive a reject notice.

Handling incoming emails requires an [IMAP](https://en.wikipedia.org/wiki/Internet_Message_Access_Protocol)-enabled
email account. GitLab requires one of the following three strategies:

- Email sub-addressing (recommended)
- Catch-all mailbox
- Dedicated email address (supports Reply by Email only)

Let's walk through each of these options.

### Email sub-addressing

[Sub-addressing](https://en.wikipedia.org/wiki/Email_address#Sub-addressing) is
a mail server feature where any email to `user+arbitrary_tag@example.com` will end up
in the mailbox for `user@example.com` . It is supported by providers such as
Gmail, Google Apps, Yahoo! Mail, Outlook.com, and iCloud, as well as the
[Postfix mail server](reply_by_email_postfix_setup.md), which you can run on-premises.

TIP: **Tip:**
If your provider or server supports email sub-addressing, we recommend using it.
A dedicated email address only supports Reply by Email functionality.
A catch-all mailbox supports the same features as sub-addressing as of GitLab 11.7,
but sub-addressing is still preferred because only one email address is used,
leaving a catch-all available for other purposes beyond GitLab.

### Catch-all mailbox

A [catch-all mailbox](https://en.wikipedia.org/wiki/Catch-all) for a domain
receives all emails addressed to the domain that do not match any addresses that
exist on the mail server.

As of GitLab 11.7, catch-all mailboxes support the same features as
email sub-addressing, but email sub-addressing remains our recommendation so that you
can reserve your catch-all mailbox for other purposes.

### Dedicated email address

This solution is relatively simple to set up: you just need to create an email
address dedicated to receive your users' replies to GitLab notifications. However,
this method only supports replies, and not the other features of [incoming email](#incoming-email).

## Set it up

If you want to use Gmail / Google Apps for incoming emails, make sure you have
[IMAP access enabled](https://support.google.com/mail/answer/7126229)
and [allowed less secure apps to access the account](https://support.google.com/accounts/answer/6010255)
or [turn-on 2-step validation](https://support.google.com/accounts/answer/185839)
and use [an application password](https://support.google.com/mail/answer/185833).

If you want to use Office 365, and two-factor authentication is enabled, make sure
you're using an
[app password](https://docs.microsoft.com/en-us/azure/active-directory/user-help/multi-factor-authentication-end-user-app-passwords)
instead of the regular password for the mailbox.

To set up a basic Postfix mail server with IMAP access on Ubuntu, follow the
[Postfix setup documentation](reply_by_email_postfix_setup.md).

### Security Concerns

**WARNING:** Be careful when choosing the domain used for receiving incoming
email.

For the sake of example, suppose your top-level company domain is `hooli.com`.
All employees in your company have an email address at that domain via Google
Apps, and your company's private Slack instance requires a valid `@hooli.com`
email address in order to sign up.

If you also host a public-facing GitLab instance at `hooli.com` and set your
incoming email domain to `hooli.com`, an attacker could abuse the "Create new
issue by email" or
"[Create new merge request by email](../user/project/merge_requests/creating_merge_requests.md#new-merge-request-by-email-core-only)"
features by using a project's unique address as the email when signing up for
Slack. This would send a confirmation email, which would create a new issue or
merge request on the project owned by the attacker, allowing them to click the
confirmation link and validate their account on your company's private Slack
instance.

We recommend receiving incoming email on a subdomain, such as
`incoming.hooli.com`, and ensuring that you do not employ any services that
authenticate solely based on access to an email domain such as `*.hooli.com.`
Alternatively, use a dedicated domain for GitLab email communications such as
`hooli-gitlab.com`.

See GitLab issue [#30366](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/30366)
for a real-world example of this exploit.

CAUTION:**Caution:**
Be sure to use a mail server that has been configured to reduce
spam.
A Postfix mail server that is running on a default configuration, for example,
can result in abuse. All messages received on the configured mailbox will be processed
and messages that are not intended for the GitLab instance will receive a reject notice.
If the sender's address is spoofed, the reject notice will be delivered to the spoofed
`FROM` address, which can cause the mail server's IP or domain to appear on a block
list.

### Omnibus package installations

1. Find the `incoming_email` section in `/etc/gitlab/gitlab.rb`, enable the feature
    and fill in the details for your specific IMAP server and email account (see [examples](#configuration-examples) below).

1. Reconfigure GitLab for the changes to take effect:

   ```shell
   sudo gitlab-ctl reconfigure
   sudo gitlab-ctl restart
   ```

1. Verify that everything is configured correctly:

   ```shell
   sudo gitlab-rake gitlab:incoming_email:check
   ```

Reply by email should now be working.

### Installations from source

1. Go to the GitLab installation directory:

   ```shell
   cd /home/git/gitlab
   ```

1. Find the `incoming_email` section in `config/gitlab.yml`, enable the feature
  and fill in the details for your specific IMAP server and email account (see [examples](#configuration-examples) below).

1. Enable `mail_room` in the init script at `/etc/default/gitlab`:

   ```shell
   sudo mkdir -p /etc/default
   echo 'mail_room_enabled=true' | sudo tee -a /etc/default/gitlab
   ```

1. Restart GitLab:

   ```shell
   sudo service gitlab restart
   ```

1. Verify that everything is configured correctly:

   ```shell
   sudo -u git -H bundle exec rake gitlab:incoming_email:check RAILS_ENV=production
   ```

Reply by email should now be working.

### Configuration examples

#### Postfix

Example configuration for Postfix mail server. Assumes mailbox `incoming@gitlab.example.com`.

Example for Omnibus installs:

```ruby
gitlab_rails['incoming_email_enabled'] = true

# The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
# The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
gitlab_rails['incoming_email_address'] = "incoming+%{key}@gitlab.example.com"

# Email account username
# With third party providers, this is usually the full email address.
# With self-hosted email servers, this is usually the user part of the email address.
gitlab_rails['incoming_email_email'] = "incoming"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "gitlab.example.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 143
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = false
# Whether the IMAP server uses StartTLS
gitlab_rails['incoming_email_start_tls'] = false

# The mailbox where incoming mail will end up. Usually "inbox".
gitlab_rails['incoming_email_mailbox_name'] = "inbox"
# The IDLE command timeout.
gitlab_rails['incoming_email_idle_timeout'] = 60

# Whether to expunge (permanently remove) messages from the mailbox when they are deleted after delivery
gitlab_rails['incoming_email_expunge_deleted'] = true
```

Example for source installs:

```yaml
incoming_email:
    enabled: true

    # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
    # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
    address: "incoming+%{key}@gitlab.example.com"

    # Email account username
    # With third party providers, this is usually the full email address.
    # With self-hosted email servers, this is usually the user part of the email address.
    user: "incoming"
    # Email account password
    password: "[REDACTED]"

    # IMAP server host
    host: "gitlab.example.com"
    # IMAP server port
    port: 143
    # Whether the IMAP server uses SSL
    ssl: false
    # Whether the IMAP server uses StartTLS
    start_tls: false

    # The mailbox where incoming mail will end up. Usually "inbox".
    mailbox: "inbox"
    # The IDLE command timeout.
    idle_timeout: 60

    # Whether to expunge (permanently remove) messages from the mailbox when they are deleted after delivery
    expunge_deleted: true
```

#### Gmail

Example configuration for Gmail/G Suite. Assumes mailbox `gitlab-incoming@gmail.com`.

NOTE: **Note:**
`incoming_email_email` cannot be a Gmail alias account.

Example for Omnibus installs:

```ruby
gitlab_rails['incoming_email_enabled'] = true

# The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
# The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
gitlab_rails['incoming_email_address'] = "gitlab-incoming+%{key}@gmail.com"

# Email account username
# With third party providers, this is usually the full email address.
# With self-hosted email servers, this is usually the user part of the email address.
gitlab_rails['incoming_email_email'] = "gitlab-incoming@gmail.com"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "imap.gmail.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 993
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = true
# Whether the IMAP server uses StartTLS
gitlab_rails['incoming_email_start_tls'] = false

# The mailbox where incoming mail will end up. Usually "inbox".
gitlab_rails['incoming_email_mailbox_name'] = "inbox"
# The IDLE command timeout.
gitlab_rails['incoming_email_idle_timeout'] = 60

# Whether to expunge (permanently remove) messages from the mailbox when they are deleted after delivery
gitlab_rails['incoming_email_expunge_deleted'] = true
```

Example for source installs:

```yaml
incoming_email:
    enabled: true

    # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
    # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
    address: "gitlab-incoming+%{key}@gmail.com"

    # Email account username
    # With third party providers, this is usually the full email address.
    # With self-hosted email servers, this is usually the user part of the email address.
    user: "gitlab-incoming@gmail.com"
    # Email account password
    password: "[REDACTED]"

    # IMAP server host
    host: "imap.gmail.com"
    # IMAP server port
    port: 993
    # Whether the IMAP server uses SSL
    ssl: true
    # Whether the IMAP server uses StartTLS
    start_tls: false

    # The mailbox where incoming mail will end up. Usually "inbox".
    mailbox: "inbox"
    # The IDLE command timeout.
    idle_timeout: 60

    # Whether to expunge (permanently remove) messages from the mailbox when they are deleted after delivery
    expunge_deleted: true
```

#### Microsoft Exchange Server

Example configurations for Microsoft Exchange Server with IMAP enabled. Since
Exchange does not support sub-addressing, only two options exist:

- Catch-all mailbox (recommended for Exchange-only)
- Dedicated email address (supports Reply by Email only)

##### Catch-all mailbox

Assumes the catch-all mailbox `incoming@exchange.example.com`.

Example for Omnibus installs:

```ruby
gitlab_rails['incoming_email_enabled'] = true

# The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
# The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
# Exchange does not support sub-addressing, so a catch-all mailbox must be used.
gitlab_rails['incoming_email_address'] = "incoming-%{key}@exchange.example.com"

# Email account username
# Typically this is the userPrincipalName (UPN)
gitlab_rails['incoming_email_email'] = "incoming@ad-domain.example.com"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "exchange.example.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 993
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = true
```

Example for source installs:

```yaml
incoming_email:
    enabled: true

    # The email address including the `%{key}` placeholder that will be replaced to reference the item being replied to.
    # The placeholder can be omitted but if present, it must appear in the "user" part of the address (before the `@`).
    # Exchange does not support sub-addressing, so a catch-all mailbox must be used.
    address: "incoming-%{key}@exchange.example.com"

    # Email account username
    # Typically this is the userPrincipalName (UPN)
    user: "incoming@ad-domain.example.com"
    # Email account password
    password: "[REDACTED]"

    # IMAP server host
    host: "exchange.example.com"
    # IMAP server port
    port: 993
    # Whether the IMAP server uses SSL
    ssl: true
```

##### Dedicated email address

Assumes the dedicated email address `incoming@exchange.example.com`.

Example for Omnibus installs:

```ruby
gitlab_rails['incoming_email_enabled'] = true

# Exchange does not support sub-addressing, and we're not using a catch-all mailbox so %{key} is not used here
gitlab_rails['incoming_email_address'] = "incoming@exchange.example.com"

# Email account username
# Typically this is the userPrincipalName (UPN)
gitlab_rails['incoming_email_email'] = "incoming@ad-domain.example.com"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "exchange.example.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 993
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = true
```

Example for source installs:

```yaml
incoming_email:
    enabled: true

    # Exchange does not support sub-addressing, and we're not using a catch-all mailbox so %{key} is not used here
    address: "incoming@exchange.example.com"

    # Email account username
    # Typically this is the userPrincipalName (UPN)
    user: "incoming@ad-domain.example.com"
    # Email account password
    password: "[REDACTED]"

    # IMAP server host
    host: "exchange.example.com"
    # IMAP server port
    port: 993
    # Whether the IMAP server uses SSL
    ssl: true
```