Re: [IPCop-user] SMTP cannot send through gateway

[David M. <da...@me...>]

On Sun, Dec 11, 2011 at 11:01 PM, Greg Rees <gre...@ho...> wrote:
>
> Now I have changed ISP and they supplied a faster D-Link modem/router so I configured it in bridge mode as previous but modem or ISP drastically reduces the internet speed after awhile. I configured D-Link modem/router to connect to ISP and IPCop to connect to D-Link modem/router via a static IP, configured all relevant ports on the D-Link router to forward to IPCop.
>
> Now my SMTP server will not send emails through the D-Link modem/router but it will send emails through my ISP's SMTP server. The error message I get in the mail logs reads:
>
> postfix/smtp[5708]: 4CDE655472: to=
> delays=353373/0.12/0/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name
> service error for name=yahoo.com.au type=MX: Host not found, try again)

A few comments on things to check and report back to the list:

1) make sure dns is resolving on the mailserver:  can you ping
yahoo.com.au _from_ _the_mailserver_machine? what about google.au?

2) Is your new ISP blocking smtp traffic?

3) Did you try the mailserver directly connected to the d-link modem
for a test (just to be sure the issue is with ipcop and not upstream
somewhere)?

4) When connected to the dlink as a bridge did it work correctly?  If
so I would verify, then ask the ISP why traffic slows down after a
while in bridge mode and sort that out if possible.

5) It looks like you are double-natting? (From dlink to ipcop, from
ipcop to mailserver)  I've heard that is not optimal, but others will
have to tell you exactly why that is.

David Meed
cc: list and Greg