Unable to send messages

[Nathanael D. Noblet]

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