Unable to send messages

Troy Carpenter troy at carpenter.cx
Tue Mar 22 17:19:30 CET 2016


I have used DuoCircle's Email Gateway product (previous known as MailHop when it was run by DynDNS) to bypass my ISP's block on port 25 in the past.  You basically set up their relay as your MX host, then it forwards email to the port you want on your mail server.  For instance, I setup postfix to listen on port 2525, opened that port on the firewall, and had DuoCircle forward my email to that port.

If I recall, there were some extra things you had to do on Kolab to account for the extra hop, especially related to SPAM detection (or you can just setup all that on the DuoCircle gateway and not have to worry about it).

Troy Carpenter
troy at carpenter.cx

-----Original Message-----
From: users-bounces at lists.kolab.org [mailto:users-bounces at lists.kolab.org] On Behalf Of Sultan Ghaznawi
Sent: Monday, March 21, 2016 6:56 PM
To: 'Thomas Spuhler' <thomas.spuhler at btspuhler.com>; users at lists.kolab.org
Subject: RE: Unable to send messages

Thanks Thomas, I called them up today. I don't have static IP but a standard broadband IP that changes every few months. My ISP is the greedy type and doesn't want to open the port. They suggest using port 26 or another email provider, go figure!

Sultan

-----Original Message-----
From: Thomas Spuhler [mailto:thomas.spuhler at btspuhler.com]
Sent: Monday, March 21, 2016 6:39 PM
To: users at lists.kolab.org
Subject: Re: Unable to send messages

On Monday, March 21, 2016 04:35:09 PM Nathanael D. Noblet wrote:
> Ah yeah, I didn't know this wasn't a 'proper' server. Outgoing port 25 
> is often blocked by residential ISP providers / plans.
> 
> So your only solution is to have a relay host somewhere publicly 
> accessible and not listening on port 25 for example. You would then 
> configure your internal postfix system to use it as a relay. Which is 
> as simple as editing main.cf and setting
> 
> relayhost = [external.host.com:1025]
> 
> for example.
> 
> --
> Nathanael
> 
> On Mon, 2016-03-21 at 18:25 -0400, Sultan Ghaznawi wrote:
> > Hi Nathanael,
> >  
> > Thanks for the pointer, I checked my firewall and I have port 25 
> > opened for bi-directional traffic. I am not sure about postfix 
> > configuration as I kept everything as default during the Kolab 
> > installation process. However, I believe Rogers (my ISP in Canada) 
> > blocks port 25. I am not sure how that works since I am able receive 
> > mail (delivered to Kolab box on port 25?).
> >  
> > Is there a way to use another port or a different protocol (e.g.
> > secure)?
> >  
> > Thanks,
> >  
> > Sultan
> >  
> > From: Nathanael Noblet [mailto:nathanael at gnat.ca]
> > Sent: Sunday, March 20, 2016 10:58 PM
> > To: Sultan Ghaznawi
> > Cc: users
> > Subject: RE: Unable to send messages
> >  
> > Hello,
> >   So the only thing I can think is that somehow your firewall is 
> > blocking outbound port 25 OR you've configured postfix to use a 
> > relay host it can't reach. Try telneting to the MX server of the 
> > outbound server you were testing to narrow it further?
> > Nathanael
> > On Mar 20, 2016 3:08 PM, Sultan Ghaznawi <shghaznawi at telusmail.net>
> > wrote:
> > Hi Nathanael,
> >  
> > Many thanks for your response. What you are suggesting is what I 
> > thought of at the first place, however, I can ping any IP address 
> > from that box without a problem and all other tools, such as yum, 
> > curl, wget and everything else works. It seems the DNS is also set 
> > up properly, the only thing that might be an issue is if for some 
> > reason the firewall within the box is rejecting outbound requests 
> > from this application on a specific port. I did run the port 
> > white-listing command before installing Kolab.
> >  
> > Any other suggestions?
> >  
> > Sultan
> >  
> > From: Nathanael Noblet [mailto:nathanael at gnat.ca]
> > Sent: Saturday, March 19, 2016 12:16 AM
> > To: Sultan Ghaznawi
> > Cc: users
> > Subject: Re: Unable to send messages
> >  
> >  
> > On Mar 18, 2016, at 9:20 PM, Sultan Ghaznawi 
> > <shghaznawi at telusmail.ne
> > t> wrote:
> >  
> > Hi Everyone,
> >  
> > I set up the Kolab 16 on CentOS 7 and everything went well. Here is 
> > what is happening:
> >  
> > 1.       I can send/receive emails between internal users (my domain
> > within the box).
> > 2.       I can receive emails sent from outside my domain over the
> > internet
> > 3.       I am unable to send out messages. I send a message, I do not
> > get an error in the UI, the /var/log/maillog shows “network is 
> > unreachable” and “timed out” messages. I ran the “lmtptest 
> > google.com” command and it shows network unreachable error.
> >  
> > It sounds like the error is completely unrelated to kolab. Can the 
> > server successfully resolve names? Does its default route work 
> > outbound? Can you grab websites using curl or wget on that server? A 
> > network unreachable error really seems unrelated to kolab or any 
> > server system at all. Try narrowing down the issue. Perhaps dig 
> > apple.com to see if you get an IP etc..
> >  
> > —
> > Nathanael
> 
> _______________________________________________
> users mailing list
> users at lists.kolab.org
> https://lists.kolab.org/mailman/listinfo/users

If you have a static IP address, you may just ask your ISP to open port 25. 

--
Best regards
Thomas Spuhler

All of my e-mails have a valid digital signature ID 60114E63

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