• Requirements
  • Email sub-addressing
  • Catch-all mailbox
  • Dedicated email address
• Accepted headers
• Rejected headers
• Set it up
  • Security concerns
  • Linux package installations
  • Self-compiled installations
  • Configuration examples
    • Postfix
    • Gmail
    • Microsoft Exchange Server
      • Catch-all mailbox
      • Dedicated email address
    • Microsoft Office 365
      • Sub-addressing mailbox
      • Catch-all mailbox
      • Dedicated email address
    • Microsoft Graph
      • Restrict mailbox access
      • Configure Microsoft Graph
  • Use encrypted credentials
• Troubleshooting
  • Email ingestion doesn’t work in 16.6.0
  • Incoming emails are rejected by providers with email address limit

Incoming email

GitLab has several features based on receiving incoming email messages:

• Reply by Email: allow GitLab users to comment on issues and merge requests by replying to notification email.
• New issue by email: allow GitLab users to create a new issue by sending an email to a user-specific email address.
• New merge request by email: allow GitLab users to create a new merge request by sending an email to a user-specific email address.
• Service Desk: provide email support to your customers through GitLab.

Requirements

We recommend using an email address that receives only messages that are intended for the GitLab instance. Any incoming email messages not intended for GitLab receive a reject notice.

Handling incoming email messages requires an IMAP-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 is a mail server feature where any email to user+arbitrary_tag@example.com ends 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, which you can run on-premises. Microsoft Exchange Server does not support sub-addressing, and Microsoft Office 365 does not support sub-addressing by default.

Catch-all mailbox

A catch-all mailbox for a domain receives all email messages addressed to the domain that do not match any addresses that exist on the mail server.

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

To set up this solution, you must create a dedicated email address to receive your users’ replies to GitLab notifications. However, this method only supports replies, and not the other features of incoming email.

Accepted headers

Email is processed correctly when a configured email address is present in one of the following headers (sorted in the order they are checked):

• To
• Delivered-To
• X-Delivered-To
• Envelope-To or X-Envelope-To
• Received
• X-Original-To
• X-Forwarded-To
• Cc

The References header is also accepted, however it is used specifically to relate email responses to existing discussion threads. It is not used for creating issues by email.

In GitLab 14.6 and later, Service Desk also checks accepted headers.

Usually, the To field contains the email address of the primary receiver. However, it might not include the configured GitLab email address if:

• The address is in the BCC field.
• The email was forwarded.

The Received header can contain multiple email addresses. These are checked in the order that they appear. The first match is used.

Rejected headers

To prevent unwanted issue creation from automatic email systems, GitLab ignores all incoming email containing the following headers:

• Auto-Submitted with a value other than no
• X-Autoreply with a value of yes

Set it up

If you want to use Gmail / Google Apps for incoming email, make sure you have IMAP access enabled and allowed less secure apps to access the account or turn-on 2-step validation and use an application password.

If you want to use Office 365, and two-factor authentication is enabled, make sure you’re using an app password 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.

Security concerns

For example, suppose your top-level company domain is hooli.com. All employees in your company have an email address at that domain through Google Workspace, and your company’s private Slack instance requires a valid @hooli.com email address 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 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 select 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 for a real-world example of this exploit.

Linux 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 below).

2. Reconfigure GitLab for the changes to take effect:

   sudo gitlab-ctl reconfigure
   
   # Needed when enabling or disabling for the first time but not for password changes.
   # See https://gitlab.com/gitlab-org/gitlab-foss/-/issues/23560#note_61966788
   sudo gitlab-ctl restart
   

3. Verify that everything is configured correctly:

   sudo gitlab-rake gitlab:incoming_email:check
   

Reply by email should now be working.

Self-compiled installations

1. Go to the GitLab installation directory:

   cd /home/git/gitlab
   

2. Install the gitlab-mail_room gem manually:

   gem install gitlab-mail_room
   

   This step is necessary to avoid thread deadlocks and to support the latest MailRoom features. See this explanation for more details.

3. 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 below).

If you use systemd units to manage GitLab:

1. Add gitlab-mailroom.service as a dependency to gitlab.target:

   sudo systemctl edit gitlab.target
   

   In the editor that opens, add the following and save the file:

   [Unit]
   Wants=gitlab-mailroom.service
   

2. If you run Redis and PostgreSQL on the same machine, you should add a dependency on Redis. Run:

   sudo systemctl edit gitlab-mailroom.service
   

   In the editor that opens, add the following and save the file:

   [Unit]
   Wants=redis-server.service
   After=redis-server.service
   

3. Start gitlab-mailroom.service:

   sudo systemctl start gitlab-mailroom.service
   

4. Verify that everything is configured correctly:

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

If you use the SysV init script to manage GitLab:

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

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

2. Restart GitLab:

   sudo service gitlab restart
   

3. Verify that everything is configured correctly:

   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 Linux package installations:

gitlab_rails['incoming_email_enabled'] = true

# The email address including the %{key} placeholder that will be replaced to reference the
# item being replied to. This %{key} should be included in its entirety within the email
# address and not replaced by another value.
# For example: emailaddress+%{key}@gitlab.example.com.
# The placeholder 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

# If you are using Microsoft Graph instead of IMAP, set this to false to retain
# messages in the inbox because deleted messages are auto-expunged after some time.
gitlab_rails['incoming_email_delete_after_delivery'] = true

# Whether to expunge (permanently remove) messages from the mailbox when they are marked as deleted after delivery
# Only applies to IMAP. Microsoft Graph will auto-expunge any deleted messages.
gitlab_rails['incoming_email_expunge_deleted'] = true

Example for self-compiled installations:

incoming_email:
    enabled: true

    # The email address including the %{key} placeholder that will be replaced to reference the
    # item being replied to. This %{key} should be included in its entirety within the email
    # address and not replaced by another value.
    # For example: emailaddress+%{key}@gitlab.example.com.
    # The placeholder 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

    # If you are using Microsoft Graph instead of IMAP, set this to false to retain
    # messages in the inbox because deleted messages are auto-expunged after some time.
    delete_after_delivery: true

    # Whether to expunge (permanently remove) messages from the mailbox when they are marked as deleted after delivery
    # Only applies to IMAP. Microsoft Graph will auto-expunge any deleted messages.
    expunge_deleted: true

Gmail

Example configuration for Gmail/Google Workspace. Assumes mailbox gitlab-incoming@gmail.com.

Example for Linux package installations:

gitlab_rails['incoming_email_enabled'] = true

# The email address including the %{key} placeholder that will be replaced to reference the
# item being replied to. This %{key} should be included in its entirety within the email
# address and not replaced by another value.
# For example: emailaddress+%{key}@gmail.com.
# The placeholder 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

# If you are using Microsoft Graph instead of IMAP, set this to false if you want to retain
# messages in the inbox because deleted messages are auto-expunged after some time.
gitlab_rails['incoming_email_delete_after_delivery'] = true

# Whether to expunge (permanently remove) messages from the mailbox when they are marked as deleted after delivery
# Only applies to IMAP. Microsoft Graph will auto-expunge any deleted messages.
gitlab_rails['incoming_email_expunge_deleted'] = true

Example for self-compiled installations:

incoming_email:
    enabled: true

    # The email address including the %{key} placeholder that will be replaced to reference the
    # item being replied to. This %{key} should be included in its entirety within the email
    # address and not replaced by another value.
    # For example: emailaddress+%{key}@gmail.com.
    # The placeholder 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

    # If you are using Microsoft Graph instead of IMAP, set this to falseto retain
    # messages in the inbox because deleted messages are auto-expunged after some time.
    delete_after_delivery: true

    # Whether to expunge (permanently remove) messages from the mailbox when they are marked as deleted after delivery
    # Only applies to IMAP. Microsoft Graph will auto-expunge any deleted messages.
    expunge_deleted: true

Microsoft Exchange Server

Example configurations for Microsoft Exchange Server with IMAP enabled. Because 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 Linux package installations:

gitlab_rails['incoming_email_enabled'] = true

# The email address including the %{key} placeholder that will be replaced to reference the
# item being replied to. This %{key} should be included in its entirety within the email
# address and not replaced by another value.
# For example: emailaddress-%{key}@exchange.example.com.
# The placeholder 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

# Whether to expunge (permanently remove) messages from the mailbox when they are marked as deleted after delivery
# Only applies to IMAP. Microsoft Graph will auto-expunge any deleted messages.
gitlab_rails['incoming_email_expunge_deleted'] = true

Example for self-compiled installations:

incoming_email:
    enabled: true

    # The email address including the %{key} placeholder that will be replaced to reference the
    # item being replied to. This %{key} should be included in its entirety within the email
    # address and not replaced by another value.
    # For example: emailaddress-%{key}@exchange.example.com.
    # The placeholder 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

    # If you are using Microsoft Graph instead of IMAP, set this to false to retain
    # messages in the inbox since deleted messages are auto-expunged after some time.
    delete_after_delivery: true

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

Dedicated email address

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

Example for Linux package installations:

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

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

Example for self-compiled installations:

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

    # If you are using Microsoft Graph instead of IMAP, set this to false to retain
    # messages in the inbox since deleted messages are auto-expunged after some time.
    delete_after_delivery: true

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

Microsoft Office 365

Example configurations for Microsoft Office 365 with IMAP enabled.

Sub-addressing mailbox

This series of PowerShell commands enables sub-addressing at the organization level in Office 365. This allows all mailboxes in the organization to receive sub-addressed mail.

To enable sub-addressing:

1. Download and install the ExchangeOnlineManagement module from the PowerShell gallery.

2. In PowerShell, run the following commands:

   Set-ExecutionPolicy RemoteSigned -Scope CurrentUser
   Import-Module ExchangeOnlineManagement
   Connect-ExchangeOnline
   Set-OrganizationConfig -AllowPlusAddressInRecipients $true
   Disconnect-ExchangeOnline
   

This example for Linux package installations assumes the mailbox incoming@office365.example.com:

gitlab_rails['incoming_email_enabled'] = true

# The email address including the %{key} placeholder that will be replaced to reference the
# item being replied to. This %{key} should be included in its entirety within the email
# address and not replaced by another value.
# For example: emailaddress+%{key}@office365.example.com.
# The placeholder must appear in the "user" part of the address (before the `@`).
gitlab_rails['incoming_email_address'] = "incoming+%{key}@office365.example.com"

# Email account username
# Typically this is the userPrincipalName (UPN)
gitlab_rails['incoming_email_email'] = "incoming@office365.example.com"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "outlook.office365.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 993
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = true

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

This example for self-compiled installations assumes the mailbox incoming@office365.example.com:

incoming_email:
    enabled: true

    # The email address including the %{key} placeholder that will be replaced to reference the
    # item being replied to. This %{key} should be included in its entirety within the email
    # address and not replaced by another value.
    # For example: emailaddress+%{key}@office365.example.com.
    # The placeholder must appear in the "user" part of the address (before the `@`).
    address: "incoming+%{key}@office365.example.comm"

    # Email account username
    # Typically this is the userPrincipalName (UPN)
    user: "incoming@office365.example.comm"
    # Email account password
    password: "[REDACTED]"

    # IMAP server host
    host: "outlook.office365.com"
    # IMAP server port
    port: 993
    # Whether the IMAP server uses SSL
    ssl: true

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

Catch-all mailbox

This example for Linux package installations assumes the catch-all mailbox incoming@office365.example.com:

gitlab_rails['incoming_email_enabled'] = true

# The email address including the %{key} placeholder that will be replaced to reference the
# item being replied to. This %{key} should be included in its entirety within the email
# address and not replaced by another value.
# For example: emailaddress-%{key}@office365.example.com.
# The placeholder must appear in the "user" part of the address (before the `@`).
gitlab_rails['incoming_email_address'] = "incoming-%{key}@office365.example.com"

# Email account username
# Typically this is the userPrincipalName (UPN)
gitlab_rails['incoming_email_email'] = "incoming@office365.example.com"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "outlook.office365.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 993
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = true

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

This example for self-compiled installations assumes the catch-all mailbox incoming@office365.example.com:

incoming_email:
    enabled: true

    # The email address including the %{key} placeholder that will be replaced to reference the
    # item being replied to. This %{key} should be included in its entirety within the email
    # address and not replaced by another value.
    # For example: emailaddress+%{key}@office365.example.com.
    # The placeholder must appear in the "user" part of the address (before the `@`).
    address: "incoming-%{key}@office365.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: "outlook.office365.com"
    # IMAP server port
    port: 993
    # Whether the IMAP server uses SSL
    ssl: true

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

Dedicated email address

This example for Linux package installations assumes the dedicated email address incoming@office365.example.com:

gitlab_rails['incoming_email_enabled'] = true

gitlab_rails['incoming_email_address'] = "incoming@office365.example.com"

# Email account username
# Typically this is the userPrincipalName (UPN)
gitlab_rails['incoming_email_email'] = "incoming@office365.example.com"
# Email account password
gitlab_rails['incoming_email_password'] = "[REDACTED]"

# IMAP server host
gitlab_rails['incoming_email_host'] = "outlook.office365.com"
# IMAP server port
gitlab_rails['incoming_email_port'] = 993
# Whether the IMAP server uses SSL
gitlab_rails['incoming_email_ssl'] = true

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

This example for self-compiled installations assumes the dedicated email address incoming@office365.example.com:

incoming_email:
    enabled: true

    address: "incoming@office365.example.com"

    # Email account username
    # Typically this is the userPrincipalName (UPN)
    user: "incoming@office365.example.com"
    # Email account password
    password: "[REDACTED]"

    # IMAP server host
    host: "outlook.office365.com"
    # IMAP server port
    port: 993
    # Whether the IMAP server uses SSL
    ssl: true

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

Microsoft Graph

GitLab can read incoming email using the Microsoft Graph API instead of IMAP. Because Microsoft is deprecating IMAP usage with Basic Authentication, the Microsoft Graph API is be required for new Microsoft Exchange Online mailboxes.

To configure GitLab for Microsoft Graph, you need to register an OAuth 2.0 application in your Azure Active Directory that has the Mail.ReadWrite permission for all mailboxes. See the MailRoom step-by-step guide and Microsoft instructions for more details.

Record the following when you configure your OAuth 2.0 application:

• Tenant ID for your Azure Active Directory
• Client ID for your OAuth 2.0 application
• Client secret your OAuth 2.0 application

Restrict mailbox access

For MailRoom to work as a service account, the application you create in Azure Active Directory requires that you set the Mail.ReadWrite property to read/write mail in all mailboxes.

To mitigate security concerns, we recommend configuring an application access policy which limits the mailbox access for all accounts, as described in Microsoft documentation.

This example for Linux package installations assumes you’re using the following mailbox: incoming@example.onmicrosoft.com:

Configure Microsoft Graph

gitlab_rails['incoming_email_enabled'] = true

# The email address including the %{key} placeholder that will be replaced to reference the
# item being replied to. This %{key} should be included in its entirety within the email
# address and not replaced by another value.
# For example: emailaddress+%{key}@example.onmicrosoft.com.
# The placeholder must appear in the "user" part of the address (before the `@`).
gitlab_rails['incoming_email_address'] = "incoming+%{key}@example.onmicrosoft.com"

# Email account username
gitlab_rails['incoming_email_email'] = "incoming@example.onmicrosoft.com"
gitlab_rails['incoming_email_delete_after_delivery'] = false

gitlab_rails['incoming_email_inbox_method'] = 'microsoft_graph'
gitlab_rails['incoming_email_inbox_options'] = {
   'tenant_id': '<YOUR-TENANT-ID>',
   'client_id': '<YOUR-CLIENT-ID>',
   'client_secret': '<YOUR-CLIENT-SECRET>',
   'poll_interval': 60  # Optional
}

For Microsoft Cloud for US Government or other Azure deployments, configure the azure_ad_endpoint and graph_endpoint settings.

• Example for Microsoft Cloud for US Government:

gitlab_rails['incoming_email_inbox_options'] = {
   'azure_ad_endpoint': 'https://login.microsoftonline.us',
   'graph_endpoint': 'https://graph.microsoft.us',
   'tenant_id': '<YOUR-TENANT-ID>',
   'client_id': '<YOUR-CLIENT-ID>',
   'client_secret': '<YOUR-CLIENT-SECRET>',
   'poll_interval': 60  # Optional
}

The Microsoft Graph API is not yet supported in self-compiled installations. See this issue for more details.

Use encrypted credentials

Instead of having the incoming email credentials stored in plaintext in the configuration files, you can optionally use an encrypted file for the incoming email credentials.

Prerequisites:

• To use encrypted credentials, you must first enable the encrypted configuration.

The supported configuration items for the encrypted file are:

• user
• password

Troubleshooting

Email ingestion doesn’t work in 16.6.0

GitLab self-managed 16.6.0 introduced a regression that prevents mail_room (email ingestion) from starting. Service Desk and other reply-by-email features don’t work. Issue 432257 tracks fixing this problem.

The workaround is to run the following commands in your GitLab installation to patch the affected files:

curl --output /tmp/mailroom.patch --url "https://gitlab.com/gitlab-org/gitlab/-/merge_requests/137279.diff"
patch -p1 -d /opt/gitlab/embedded/service/gitlab-rails < /tmp/mailroom.patch
gitlab-ctl restart mailroom

curl --output /tmp/mailroom.patch --url "https://gitlab.com/gitlab-org/gitlab/-/merge_requests/137279.diff"
cd /opt/gitlab/embedded/service/gitlab-rails
patch -p1 < /tmp/mailroom.patch
gitlab-ctl restart mailroom

Incoming emails are rejected by providers with email address limit

Your GitLab instance might not receive incoming emails, because some email providers impose a 64-character limit on the local part of the email address (before the @). All emails from addresses that exceed this limit are rejected emails.

As a workaround, maintain a shorter path:

• Ensure that the local part configured before %{key} in incoming_email_address is as short as possible, and not longer than 31 characters.
• Place the designated projects at a higher group hierarchy.
• Rename groups and project to shorter names.

Track this feature in issue 460206.