This guide will walk you through configuring Exim to use JetEmail as your smarthost for improved email deliverability and authentication.

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Prerequisites

  • Root access to your server
  • Exim mail server installed and running
  • JetEmail SMTP credentials from your dashboard

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Configuration Steps

1

Generate SMTP Credentials

Create a smarthost (or use an existing one) in your JetEmail dashboard.
2

Configure Authentication

Add the following to your Exim configuration file (typically /etc/exim4/exim4.conf.template or /etc/exim.conf):
# JetEmail Authentication
jetemail_login:
  driver = plaintext
  public_name = LOGIN
  client_send = : your_username : your_password
Replace your_username and your_password with your JetEmail SMTP credentials.
3

Configure Transport

Add the transport configuration:
# JetEmail SMTP Transport
jetemail_smtp:
  driver = smtp
  hosts_require_auth = *
  tls_tempfail_tryclear = true
  headers_add = X-AuthUser: your_username
  hosts_try_chunking =
  hosts_try_fastopen =
  dkim_domain = ${lc:${domain:$h_from:}}
  dkim_selector = default
  dkim_private_key = /path/to/dkim/private/${dkim_domain}
Update the dkim_private_key path to match your DKIM key location.
4

Configure Router

Add the router configuration to send mail via JetEmail:
# JetEmail Smarthost Router
send_via_jetemail:
  driver = manualroute
  domains = ! +local_domains
  ignore_target_hosts = 127.0.0.0/8
  transport = jetemail_smtp
  route_list = * relay.jetsmtp.net::25 randomize byname
  no_more
5

Optional: Configure SRS (Sender Rewriting Scheme)

For email forwarding scenarios, add SRS support:
# SRS Transport for forwarded emails
jetemail_forward_smtp:
  driver = smtp
  hosts_require_auth = *
  tls_tempfail_tryclear = true
  headers_add = X-AuthUser: your_username
  hosts_try_chunking =
  hosts_try_fastopen =
  dkim_domain = ${lc:${domain:$h_from:}}
  dkim_selector = default
  dkim_private_key = /path/to/dkim/private/${dkim_domain}
  return_path = ${srs_encode {SRS_SECRET} {$return_path} {$original_domain}}
  max_rcpt = 1
6

Test and Restart Exim

Test your configuration and restart Exim:
exim -bV  # Test configuration syntax
systemctl restart exim4  # Debian/Ubuntu
# OR
systemctl restart exim   # CentOS/RHEL

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Additional Configuration

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SPF Records

Don’t forget to update your SPF records to include JetEmail’s servers: 
v=spf1 include:spf.jetsmtp.net ~all
Learn more about SPF configuration.

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Domain Authentication

For enhanced security and deliverability:
  • Configure Domain Lockdown to prevent domain spoofing
  • Set up DMARC for email authentication
  • Ensure proper DKIM signing is configured

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Testing Your Configuration

After configuration, test your setup:
  1. Send a test email to an external address
  2. Check email headers for authentication details: 
    echo "Test message" | mail -s "Test Subject" [email protected]
  3. Monitor delivery in your JetEmail dashboard
  4. Verify SPF, DKIM, and DMARC alignment

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Troubleshooting

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Authentication Failures

  • Verify your SMTP credentials are correct
  • Ensure your account is active and in good standing
  • Check that authentication headers are properly configured

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Connection Issues

  • Verify ports 25 or 587 are open in your firewall
  • Test connectivity to relay.jetsmtp.net: 
    telnet relay.jetsmtp.net 25
  • Check TLS configuration

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Configuration Errors

  • Check Exim logs for error messages: 
    tail -f /var/log/exim4/mainlog  # Debian/Ubuntu
tail -f /var/log/exim/main.log  # CentOS/RHEL
  • Verify configuration syntax with exim -bV

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Control Panel Integration

If you’re using a control panel, consider using our automated solutions instead: For additional support, contact our team or visit our Discord community.