Can NethServer be used to send messages to external email addresses?

I’m continuing to play with a new NethServer 6.8 installation, and I’m trying to figure out if/how NethServer can be configured to send email to external email addresses. From the NethServer documentation (

NethServer can handle an unlimited number of mail domains, configurable from the Email
Domains page. For each domain there are two alternatives:

Deliver messages to local mailboxes, according to the Maildir [8] format.
Relay messages to another mail server.

So am I correct in saying that NethServer isn’t meant to be used to send email to external email addresses? I see that you can relay email to an external mail server, but what about just using Postfix already installed with NethServer?

A little background for why I want to do this: I’m in the middle of installing Mail Piler on my NethServer box, and it appears I need an SMTP server in order to forward archived emails to users. The idea is that a user can “restore” an email that has been archiving in Mail Piler. This “restore” function just forwards the email to the user. My plan was to use Postfix to send the email to the user since my production mail server is on VPS elsewhere (MailEnable v9.0.x on MS Server 2012).

Any assistance would be greatly appreciated. I’m a Linux noob and I don’t have much experience with mail servers in general. Thanks for everyone’s assistance and patience!

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Hi @FauxAnonymity,

Yes it does, with the default Postfix configuration!

Let me know how it goes with Mail Piler!

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Hi @davidep,

Thanks for confirming NethServer does in fact support sending email to external email addresses! From the documentation, I wasn’t really sure. I’m still not entirely certain how to go about doing that, though. I’m not entirely certain that I’m going to be using the Postfix SMTP server now that I don’t a little more reading up on the configuration settings for Mail Piler, though. Mail Piler has its own SMTP server and it’s suggested to turn off Postfix. The Mail Piler documentation mentions that you can just run Postfix on a different port if you want to use Postfix to handle sending any archived mail to the user, but seeing as I’m already pretty confused with the setup, I’m just going to try to use my current MailEnable production mail server to handle the role of emailing to external email addresses (when forwarding emails to users from their archive).

For future reference, however (since I plan on running another NethServer box where I do intend on running Postfix as my SMTP server for intranet and internet email transport), can you give me some hints or direction for how to use Postfix for sending email to external email addresses? I’ve found multiple articles that talk about setting up mail servers on a DMZ network attached to your server. Is that what I should be doing here? Should I create an Orange (DMZ) zone using the VLAN option and then somehow change the Postfix configuration so that it “lives” in the Orange zone? Clearly, my main problem is a fundamental lack of understanding regarding the different parts of mail servers (MTA, MDA, etc), so I’m trying to find some references that spells out everything for me. In the meantime, if you can point me in the direction of how I’d use the default Postfix configuration to send emails to external email addresses, I’d be very grateful!

Thanks again, @davidep!!

P.S. - So far, so good with Mail Piler. Once I get the ability to forward archived emails back to the user’s mailbox on my production server (on a VPS with HostDime), then I’ll be VERY happy!

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I forgot to add a brief description of my current NethServer configuration:

  1. I set up my NethServer installation as a PDC with an internal domain of mycompany.lan
  2. Here’s my general hardware setup:
    Internet (Verizon FiOS) ==> Verizon Actiontec Router (IP: ==(eth1, red) ==> NethServer desktop ==(eth0, green)==> Switch ==> Win8.1 laptop, Win7 laptop, other clients
  3. I planned to use a FQDN (; got it for cheap on NameCheap) to send email to external email addresses. I thought I should enter that domain in the NethServer email section of the web GUI, but the two available options (messages to this domain are delivered locally OR messages to this domain are relayed to another server) initially confused me. Now that I think about it (whilst fully awake), I believe I just want the messages delivered locally.

Once I have the email domain created, and I create an email address, should I be able to send emails to external email addresses without making any firewall rules or port forwarding adjustments?

No adjustments should be required on the NethServer itself. However the network router could have a restricted policy about SMTP.