zulip/docs/production/email-gateway.md

Incoming email integration

Zulip's incoming email gateway integration makes it possible to send messages into Zulip by sending an email. It's highly recommended because it enables:

• When users reply to one of Zulip's message notification emails from their email client, the reply can go directly into Zulip.
• Integrating third-party services that can send email notifications into Zulip. See the integration documentation for details.

Once this integration is configured, each channel will have a special email address displayed on the channel settings page. Emails sent to that address will be delivered into the channel.

There are two ways to configure Zulip's email gateway:

1. Local delivery (recommended): A postfix server runs on the Zulip server and passes the emails directly to Zulip.
2. Polling: A cron job running on the Zulip server checks an IMAP inbox (username@example.com) every minute for new emails.

The local delivery configuration is preferred for production because it supports nicer looking email addresses and has no cron delay. The polling option is convenient for testing/developing this feature because it doesn't require a public IP address, setting up MX records in DNS, or adjusting firewalls.

:::{note} Incoming emails are rate-limited, with the following limits:

• 50 emails per minute.
• 120 emails per 5 minutes.
• 600 emails per hour.

:::

Local delivery setup

Zulip's Puppet configuration provides everything needed to run this integration; you just need to enable and configure it as follows.

The main decision you need to make is what email domain you want to use for the gateway; for this discussion we'll use emaildomain.example.com. The email addresses used by the gateway will look like foo@emaildomain.example.com, so we recommend using EXTERNAL_HOST here.

We will use hostname.example.com as the hostname of the Zulip server (this will usually also be the same as EXTERNAL_HOST, unless you are using an HTTP reverse proxy).

1. Using your DNS provider, create a DNS MX (mail exchange) record configuring email for emaildomain.example.com to be processed by hostname.example.com. You can check your work using this command:

   $ dig +short emaildomain.example.com -t MX
   1 hostname.example.com
   

2. If you have a network firewall enabled, configure it to allow incoming access to port 25 on the Zulip server from the public internet. Other mail servers will need to use it to deliver emails to Zulip.

3. Log in to your Zulip server; the remaining steps all happen there.

4. Add , zulip::postfix_localmail to puppet_classes in /etc/zulip/zulip.conf. A typical value after this change is:

   puppet_classes = zulip::profile::standalone, zulip::postfix_localmail
   

5. If hostname.example.com is different from emaildomain.example.com, add a section to /etc/zulip/zulip.conf on your Zulip server like this:

   [postfix]
   mailname = emaildomain.example.com
   

   This tells postfix to expect to receive emails at addresses ending with @emaildomain.example.com, overriding the default of @hostname.example.com. It will also identify itself as emaildomain.example.com on any outgoing emails it sends.

6. Run /home/zulip/deployments/current/scripts/zulip-puppet-apply (and answer y) to apply your new /etc/zulip/zulip.conf configuration to your Zulip server.

7. Edit /etc/zulip/settings.py, and set EMAIL_GATEWAY_PATTERN to "%s@emaildomain.example.com".

8. Restart your Zulip server with /home/zulip/deployments/current/scripts/restart-server.

Congratulations! The integration should be fully operational.

Polling setup

1. Create an email account dedicated to Zulip's email gateway messages. We assume the address is of the form username@example.com. The email provider needs to support the standard model of delivering emails sent to username+stuff@example.com to the username@example.com inbox.

2. Edit /etc/zulip/settings.py, and set EMAIL_GATEWAY_PATTERN to "username+%s@example.com".

3. Set up IMAP for your email account and obtain the authentication details. (Here's how it works with Gmail)

4. Configure IMAP access in the appropriate Zulip settings:

   • Login and server connection details in /etc/zulip/settings.py in the email gateway integration section (EMAIL_GATEWAY_LOGIN and others).
   • Password in /etc/zulip/zulip-secrets.conf as email_gateway_password.

5. Test your configuration by sending emails to the target email account and then running the Zulip tool to poll that inbox:

   su zulip -c '/home/zulip/deployments/current/manage.py email_mirror'
   

6. Once everything is working, install the cron job which will poll the inbox every minute for new messages using the tool you tested in the last step:

   cd /home/zulip/deployments/current/
   sudo cp puppet/zulip/files/cron.d/email-mirror /etc/cron.d/
   

Congratulations! The integration should be fully operational.