Re: [gentoo-server] Strange Mailserver Problem with dynamic DN

[Florian Sesser]

Hi,

My first guess would be that your ISP, solnet, is blocking your port 25.

Their MX can connect to yours because it is in 'their' network, but their
firewall rules prohibit anything coming from their upstream provider to
connect to their clients (maybe to prevent spam or what ever, maybe just
for lameness).

You could ask your provider for being unblocked (dumb idea when using a
large ISP?). I don't know about your DynDNS provider, but if you really
need a local MX you could switch to no-ip.com: they offer some service to
get exactly around the problem you have, pretty cheap IIRC. I don't know
how they implement this, i guess they set the DNS MX records to one of
their servers and then forward them to some other port on your machine.

> I am using DNS Made Easy (like DynDNS) to point my Domain to my dynamic
> IP address. Now almost everthing works. I can send mails outside my
> domain but when I want to send an email to myself something strange
> happens:
> When I send an Email from my ADSL provider (solnet.ch) then I can
> receive the email. Here the postfix log:
>
[... mucho log entrys only showing mail which is properly received ...]
>
> But when I send a message from another account (bluewin.ch) then I NEVER
> receive the mail and I get no error messages. It seems that those emails
> go to nirvana without notification.

i don't know about how mail servers react to ports being blocked. could be
some/most/all really give up w/o notification. If Solnet *drops* packets
to your port 25 this is probable. (someone correct me on this one if i'm
wrong please?)

HTH,

Flo