LiquidFiles Documentation

This article covers how LiquidFiles deliver emails and how you can configure LiquidFiles to relay emails through another mail server or SMTP gateway.

Sending From the System or the Logged in Users Email Address

Starting with LiquidFiles v3.0, LiquidFiles defaults to send all emails from the configured system email address. Please see the following screenshot:


With this configuration, all emails sent from this LiquidFiles system will use the From email address ''. If you configure an Email Relay, you can use this address as the authenticating email address and Emails will likely flow nicely.

If you unselect the "Use the Email Sender Address for all emails", then when a user logged in as sends a message, the email From address will be: ''. This is strictly speaking more correct as the recipient will receive the email from the email of the actual user.

The challenge with not Using the Email Sender Address for all emails is that a lot of email systems like Exchange and Office 365 will not allow any sender to be used. This can be especially challenging for external users where things like external SPF configuration can interfere with the delivery of emails from the LiquidFiles system.

Direct or Email Relay Delivery

LiquidFiles can either deliver emails directly from the LiquidFiles system itself or you can use an email relay system, like your corporate email server or dedicated SMTP gateway. Both have their pros and cons. Please consider the following:


Direct Delivery (no email relay)

For direct delivery, lets say that we're sending a message to The following steps will be taken:

  1. Query the DNS server for the MX record for (in english the query would be: which is the email server that I should deliver emails to for the domain
  2. The DNS server responds with an IP address (both a name, like, and the ip address for to be precise).
  3. The LiquidFiles Appliance connects to the ip address in the DNS response and tries to deliver the email.

For this to work, you will need to make sure that the LiquidFiles system can access a DNS server (you pretty much need this regardless if you're delivering emails direct or not) and can connect to the Internet using SMTP (TCP/25).

It would also be strongly advisable to ensure that:

  • The LiquidFiles external IP address is in a static network range and not in a ISP "home user" network.
  • The LiquidFiles external IP address is configured with a reverse lookup DNS address.
  • The LiquidFiles external IP address is not listed as a known spammer ip address in anti-spam services like SpamHaus.
  • If you have configured SPF in your DNS server, you will need to update it to include the LiquidFiles external IP address.

A couple of these can be directly checked from the LiquidFiles system itself.

Please go to Admin → System → Status, and you will see the following sections:


In this example you can see that the IP address for this system:, currently does not have a reverse lookup address configured in DNS. This needs to be fixed. But, the IP address is not currently listed in the SpamHaus list of know spammer IP address, which is very good.

With the correct network/DNS configuration as outlined in this section LiquidFiles will deliver emails directly to end recipients just fine.

Email Relay Configuration

You can also configure LiquidFiles to send emails by relaying emails through another email server or SMTP gateway. Configuration is very straight forward, please see the following screenshot:


Using the same example as above, in the case of Email Relay Delivery, sending a message to, the following steps will be taken:

  • The LiquidFiles Appliance delivers the email to the configured email relay server.
  • The email relay server will lookup DNS and send the email to the recipient.

All the same network and DNS considerations as in the direct email delivery still applies, but in this case for the email server, not LiquidFiles, and in case there's any issues all emails out from the email server or SMTP gateway would be affected.