SMTP email setup

To run in production, Mattermost requires SMTP email to be enabled for email notifications and password reset for systems using email-based authentication.

How to enable email

To enable email, configure an SMTP email service as follows:

Set up an SMTP email sending service (if you don’t yet have an SMTP service with credentials)
- Any SMTP email service can be used, you just need the following information: Server Name, Port, SMTP Username, and SMTP Password.
- If you don’t have an SMTP service you can set one up with:
  Amazon Simple Email Service (SES):
  
  Go to Amazon SES console then
  SMTP Settings > Create My SMTP Credentials
  
  Copy the Server Name, Port, SMTP Username, and
  SMTP Password for Step 2 below.
  
  From the Domains menu set up and verify a new domain,
  then enable Generate DKIM Settings for the domain.
  
  1. We recommend you set up Sender Policy Framework (SPF) and/or Domain Keys Identified Mail (DKIM) for your email domain.
  
  Choose a sender address like mattermost@example.com and
  select Send a Test Email to verify setup is working correctly.
  
  By local sendmail can be used by using Server Name 127.0.0.1 with Port 25
  
  Or by using one of the services listed below in the Sample SMTP Settings
Configure SMTP settings
1. Go to Product menu > System Console.
  - Alternatively, if a team doesn’t yet exist navigate to your serverURL and select Go To System Console.
2. Go to the Authentication > Email tab and configure the following:
  1. Allow Sign Up With Email: true
3. Go to the Notifications > Email tab and configure the following:
  1. Send Email Notifications: true
  2. Notification Display Name: Display name on email account sending notifications
  3. Notification Email Address: Email address displayed on email account used to send notifications
  4. SMTP Username: SMTP Username from Step 1
  5. SMTP Password: SMTP Password from Step 1
  6. SMTP Server: SMTP Server from Step 1
  7. SMTP Port: SMTP Port from Step 1
  8. Connection Security: TLS (Recommended)
  9. Then select Save
  10. Then select Test Connection
  11. If the test failed please look in OTHER > Logs for any errors that look like [ERROR] /api/v4/email/test ...
4. (Optional) Go to the Security > Sign Up tab and configure the following:
  1. Enable Email Invitations: true

Sample SMTP settings

Amazon SES

Set SMTP Username to [YOUR_SMTP_USERNAME]
Set SMTP Password to [YOUR_SMTP_PASSWORD]
Set SMTP Server to email-smtp.us-east-1.amazonaws.com
Set SMTP Port to 465
Set Connection Security to TLS

Postfix

Make sure Postfix is installed on the machine where Mattermost is installed
Set SMTP Username to (empty)
Set SMTP Password to (empty)
Set SMTP Server to localhost
Set SMTP Port to 25
Set Connection Security to (empty)

Gmail

Set SMTP Username to your_email@gmail.com
Set SMTP Password to your_password
Set SMTP Server to smtp.gmail.com
Set SMTP Port to 587
Set Connection Security to STARTTLS

Warning

Additional configuration is required in Google to allow SMTP email to relay through their servers. See SMTP relay: Route outgoing non-Gmail messages through Google for the required steps.

Hotmail

Set SMTP Username to your_email@hotmail.com
Set SMTP Password to your_password
Set SMTP Server to smtp-mail.outlook.com
Set SMTP Port to 587
Set Connection Security to STARTTLS

Office365/Outlook

Set SMTP Username to your_email@hotmail.com
Set SMTP Password to your_password
Set SMTP Server Name to smtp.office365.com
Set SMTP Port to 587
Set Connection Security to STARTTLS

Troubleshooting SMTP

TLS/STARTTLS requirements

If you fill in SMTP Username and SMTP Password then you must set Connection Security to TLS or to STARTTLS

Troubleshooting using Logs

If you have issues with your SMTP install, from your Mattermost team site go to System Console > Logs to look for error messages related to your setup. You can do a search for the error code to narrow down the issue. Sometimes ISPs require nuanced setups for SMTP and error codes can hint at how to make the proper adjustments.

For example, if System Console > Logs has an error code reading:

Connection unsuccessful: Failed to add to email address - 554 5.7.1 <unknown[IP-ADDRESS]>: Client host rejected: Access denied

Search for 554 5.7.1 error and Client host rejected: Access denied.

Checking your SMTP server is reachable

Attempt to Telnet to the email service to make sure the server is reachable. For additional information, visit https://docs.microsoft.com/en-us/exchange/mail-flow/test-smtp-with-telnet?view=exchserver-2019. If you’re using an earlier version than Exchange Server 2019, select your version from the left-hand navigation menu.
You must run the following commands from the same machine or virtual instance where mattermost/bin/mattermost is located.
Telnet to the email server with telnet mail.example.com 25. If the command works you should see something like:
```
Trying 24.121.12.143...
Connected to mail.example.com.
220 mail.example.com NO UCE ESMTP
```
Then type something like HELO <your mail server domain>. If the command works you should see something like:
```
250-mail.example.com NO UCE
250-STARTTLS
250-PIPELINING
250 8BITMIME
```

Note

As we’re not installing telnet by default on the official docker images, you either need to use ping on those or install telnet yourself either directly or by modifying the Dockerfile.
For further assistance, review the Troubleshooting forum for previously reported errors, or join the Mattermost user community for troubleshooting help. To submit an improvement or correction to this page, select Edit in the top-right corner of the page.