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ecanmaster
20-Jan-2015, 15:46
I have sles 11 sp2 running on couple of servers, which are on a subnets that doesn't have internet access.
On one of the systems there is a program running and needs to send email alerts.
The issue is on how to send emails to a different subnet which has access to the internet, because on another subnet we do have internet access.
Let me know if you need more info.


thx

jmozdzen
20-Jan-2015, 15:59
Hi ecanmaster,

I have sles 11 sp2 running on couple of servers, which are on a subnets that doesn't have internet access.
On one of the systems there is a program running and needs to send email alerts.
The issue is on how to send emails to a different subnet which has access to the internet, because on another subnet we do have internet access.

you'll need a relay MTA (mail transfer agent) that is able to forward your emails to the Internet, and would point your server's MTA (Postfix) to that MTA server. If you're not handling mail at all on these non-Internet servers so far, I'd assume a "nullclient" configuration would be sufficient (so that *all* mail from your server gets redirected) - you'd only need to set POSTFIX_RELAYHOST to point to the relay MTA, and set POSTFIX_NULLCLIENT to "yes" (in /etc/sysconfig/postfix) and rerun /usr/sbin/SuSEconfig.postfix.

Things get a bit more complicated if you need a finer level of control. You may notice that more emails get sent than you expected (not only from your application), so make sure to talk to your mail admin before implementing this.

And please make sure you're sending emails with working reply-to addresses.

Regards,
Jens

ecanmaster
20-Jan-2015, 16:30
Hello Jens,

Thank you for your quick reply.
I only need to send message and not receive any.
So a "null" configuration sounds good.
About the MTA, can I install that on the current server or should it be installed on a server connected to the internet?

Thx.

jmozdzen
20-Jan-2015, 16:46
Hi ecanmaster,

About the MTA, can I install that on the current server or should it be installed on a server connected to the internet?

make that "on both", and you probably already have that software installed - Postfix is an MTA and installed per default.

If you not yet have *any* outgoing email configuration, things will get more complicated: Nowadays, rather often you'll find that you cannot simply have your MTA forward mails to some remote MTA - thanks to spam blocking policies, often only "trusted" MTAs are accepted. So what you'll typically end up doing is configuring your Internet provider's MTA as the proxy to use, which will in turn forward these emails to the destination and act as a trusted source. But in order to only permit emails from its customers, the provider will have some measure in place to make sure you're a customer. The procedures vary (login, send after poll,...), you'll have to look that up.

If you really need to set up "the MTA" for your site, I suggest to get some assistance. Things can get rather complex pretty fast and you need a sound understanding of what you're looking at, to avoid pot holes and nastinesses (like turning out to be a public spam relay).

If OTOH your site already has some server for outgoing emails, use that - definitely easier to set up, since you can skip the whole part of Internet-based forwarding.

Regards,
Jens

ecanmaster
20-Jan-2015, 17:03
Hello Jens,

This problems looks more like a network problem instead of email configuration.
In order to set this up, I need internet connection and no other servers have internet connection (security issue).
I might setup a second network interface connecting to the subnet which has internet, but it's probably not allowed.
Seems I have to skip the email alerts.

Thx.