Gateway Mode Deployment

Gateway mode deployment

After completing the Quick Start Wizard, you may need to configure some items that are specific to your network topology or the operation mode of your FortiMail unit.

This section contains examples of how to deploy a FortiMail unit operating in gateway mode. Other sections discuss deployment in the other two modes.

This section includes the following topics:

  • Configuring DNS records
  • Example 1: FortiMail unit behind a firewall
  • Example 2: FortiMail unit in front of a firewall
  • Example 3: FortiMail unit in DMZ

Configuring DNS records

You must configure public DNS records for the protected domains and for the FortiMail unit itself.

For performance reasons, and to support some configuration options, you may also want to provide a private DNS server for exclusive use by the FortiMail unit.

This section includes the following:

  • Configuring DNS records for the protected domains
  • Configuring DNS records for the FortiMail unit itself
  • Configuring a private DNS server

Configuring DNS records for the protected domains

Regardless of your private network topology, in order for external MTAs to deliver email through the FortiMail unit, you must configure the public MX record for each protected domain to indicate that the FortiMail unit is its email gateway.

For example, if the fully qualified domain name (FQDN) of the FortiMail unit is fortimail.example.com, and example.com is a protected domain, the MX record for example.com would be:

example.com IN MX 10 fortimail.example.com

If your FortiMail unit will operate in gateway mode, configure the MX record to refer to the FortiMail unit, and remove other MX records. If you fail to do so, external MTAs may not be able to deliver email to or through the FortiMail unit, or may be able to bypass the FortiMail unit by using the other MX records. If you have configured secondary MX records for failover reasons, consider configuring FortiMail high availability (HA) instead. For details, see “FortiMail high availability modes” on page 23.

An A record must also exist to resolve the host name of the FortiMail unit into an IP address.

For example, if the MX record indicates that fortimail.example.com is the email gateway for a domain, you must also configure an A record in the example.com zone file to resolve fortimail.example.com into a public IP address: fortimail IN A 10.10.10.1

where 10.10.10.1 is either the public IP address of the FortiMail unit, or a virtual IP address on a firewall or router that maps to the private IP address of the FortiMail unit.

If your FortiMail unit will relay outgoing email, you should also configure the public reverse DNS record. The public IP address of the FortiMail unit, or the virtual IP address on a firewall or router that maps to the private IP address of the FortiMail unit, should be globally resolvable into the FortiMail unit’s FQDN. If it is not, reverse DNS lookups by external SMTP servers will fail.

For example, if the public network IP address of the FortiMail unit is 10.10.10.1, a public DNS server’s reverse DNS zone file for the 10.10.10.0/24 subnet might contain:

1 IN PTR fortimail.example.com.

where fortimail.example.com is the FQDN of the FortiMail unit.

Configuring DNS records for the FortiMail unit itself

In addition to that of protected domains, the FortiMail unit must be able to receive web connections, and send and receive email, for its own domain name. Dependent features include:

  • delivery status notification (DSN) email
  • spam reports
  • email users’ access to their per-recipient quarantined mail
  • FortiMail administrators’ access to the web UI by domain name
  • alert email
  • report generation notification email

For this reason, you should also configure public DNS records for the FortiMail unit itself.

Appropriate records vary by whether or not you configured Web release host name/IP (located in AntiSpam > Quarantine > Quarantine Report in the advanced mode of the web UI).

See the following:

  • Case 1: Web Release Host Name/IP is empty/default
  • Case 2: Web Release Host Name/IP is configured

Case 1: Web Release Host Name/IP is empty/default

When Web release host name/IP is not configured (the default), the web release/delete links that appear in spam reports use the fully qualified domain name (FQDN) of the FortiMail unit. For example, if the FortiMail unit’s host name is fortimail, and its local domain name is example.net, resulting in the FQDN fortimail.example.net, a spam report’s default web release link might look like (FQDN highlighted in bold):

https://fortimail.example.net/releasecontrol?release=0%3Auser2%40examp le.com%3AMTIyMDUzOTQzOC43NDJfNjc0MzE1LkZvcnRpTWFpbC00MDAsI0YjUyM2N TkjRSxVMzoyLA%3D%3D%3Abf3db63dab53a291ab53a291ab53a291

In the DNS configuration to support this and the other DNS-dependent features, you would configure the following three records:

example.net IN MX 10 fortimail.example.net fortimail IN A 10.10.10.1 1 IN PTR fortimail.example.net.

where:

  • net is the local domain name to which the FortiMail unit belongs; in the MX record, it is the local domain for which the FortiMail is the mail gateway
  • example.net is the FQDN of the FortiMail unit
  • fortimail is the host name of the FortiMail unit; in the A record of the zone file for example.net, it resolves to the IP address of the FortiMail unit for the purpose of administrators’ access to the web UI, email users’ access to their per-recipient quarantines, to resolve the FQDN referenced in the MX record when email users send Bayesian and quarantine control email to the FortiMail unit, and to resolve to the IP address of the FortiMail unit for the purpose of the web release/delete hyperlinks in the spam report
  • 10.10.1 is the public IP address of the FortiMail unit

Having trouble configuring your Fortinet hardware or have some questions you need answered? Ask your questions in the comments below!!! Want someone else to deal with it for you? Get some consulting from Fortinet GURU!

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