I'm trying to figure out how to setup the network to serve multiple organization e-mail server through the same WAN IP.

It can be done with a multi organization e-mail server, but is there a way to set it up using multiple, single organization, e-mail servers?

The only way I can conceive, is through port translation in the port forwarding on the router, e.g.:

IMAP service of the e-mail server1 (mail.domain1.com) is offered on port 25000

SMTP service of the e-mail server1 (mail.domain1.com) is offered on port 35000

IMAP service of the e-mail server2 (mail.domain2.com) is offered on port 25001

SMTP service of the e-mail server2 (mail.domain2.com) is offered on port 35001

IMAP service of the e-mail server3 (mail.domain3.com) is offered on port 25002

SMTP service of the e-mail server3 (mail.domain3.com) is offered on port 35002


Is there a better solution?

Thank you

What I would like to accomplish is to find an easy solution, to serve multiple e-mail domains inside a single company, with an unique WAN IP.

I could opt for a multi organization e-mail server, like Zimbra, Zarafa, but I would like to continue to use Zentyal, Nethserver solutions, without delving too much into new e-mail server solutions.

Now I'm doing a lot of experimentation, before to accomplish this in production environments, trying to find the best, and easier, solutions based on my skills and needs.

Both Zentyal and Nethserver, can be adapted to serve this purpose, but they are conceived for a single organization: each e-mail address is associated to an user of the same local domain, so I need to use alias and similar. Making the whole thing a mess.

Usually, my customers use max 2 or 3 e-mail domains, so would be very easy to use 2 or 3 VMs, each one serving e-mail for a domain. And, moreover, very often it happens that my customers ask me to use an additional e-mail domain, after many years using just one. It would be easier for me, just to add a VM with another e-mail server instance, instead to change the e-mail server from ground up, so needing to migrate all the existent e-mails...

A solution would be just start to use a multi organization capable e-mail server since the beginning, so to be abble to add a domain when needed.

Just trying to understand if there is a way to continue to use the existent e-mail server, just adding a new one. 99% of times, everything resides inside an virtualization server, so would be very easy, just to add a new e-mail server.

Thank you for the suggestions, of course the lack of knowledge about the subject, is the culprit

  • 3
    Yah, this is most certainly not the way to solve this problem. Tim below gives great advice. Either do that, or even better yet, use a third-party hosted email solution, as you are very likely going to run into email reliability/deliverability issues with your setup. – EEAA Dec 11 '16 at 19:22
  • I've converted your (non-)answer into an edit to your question. Please check if this needs further editing to be one comprehensive question. – Sven Dec 11 '16 at 21:25
  • Zentyal is just a repackaged linux distribution, they haven't even come up with an original logo - somewhere in there is a bog standard email server - probably postfix, sendmail, exim or qmail, each of which cane accomodate your requirements on a single ip/smtp port/imap port. Despite all the open source software, you need to be paying them to use the software - so they should be providing support. – symcbean Dec 12 '16 at 3:15

An email server can server as many domains as required using a single IP. You would simply configure the email server to accept those domains, then point DNS MX entries at the server. SMTP and IMAP are served on standard ports. Ports don't change based on domain.

Suggest you need to hire a professional to implement this for you if you don't understand email.

Update These days you would need a really good reason to run your own email server. You'd be far better off outsourcing this. Set them up on Google Apps, FastMail, Office 365, Zoho, or any of the others. They'll give you many more features (for example calendaring and others), good spam filters, and do some user support for you, likely for less than $5 per user per month. It's unlikely to be worth your time to do this.

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