smtp connetion refused to t-online

[Florian Leibenzeder <leibenzf@xxxxxxxxxxxxxxxxxxxx>]

Hi, 

I think this topic has been discussed before to some extend but I did
not really find an answer to it.

The problem is, that my qmail does not send messages to t-online.de
adresses.
tcpdumping reveals a:
tcpdump: listening on ppp0
15:35:09.201929 217.228.147.62 > 194.25.134.8: icmp: echo request
15:35:09.231929 217.228.147.62.38165 > 194.25.134.8.http: . ack
2776826944 win 2048
15:35:09.281929 194.25.134.8 > 217.228.147.62: icmp: echo reply
15:35:09.551929 217.228.147.62.1129 > 212.185.255.231.domain:  12091+
PTR? 8.134.25.194.in-addr.arpa. (43) (DF)
15:35:09.621929 212.185.255.231.domain > 217.228.147.62.1129:  12091
1/5/5 PTR[|domain]
15:35:09.641929 217.228.147.62.38145 > 194.25.134.8.smtp: S
2702056999:2702056999(0) win 2048
15:35:09.981929 217.228.147.62.38146 > 194.25.134.8.smtp: S
1605932930:1605932930(0) win 2048
15:35:10.311929 217.228.147.62.38147 > 194.25.134.8.smtp: S
57724682:57724682(0) win 2048
15:35:10.371929 194.25.134.8 > 217.228.147.62: icmp: 194.25.134.8 tcp
port smtp unreachable [tos 0xc0]

but this IP is clearly one of their mail servers. I also can't telnet to
it form my machine but can do so from other machines on the internet. 
I have to add, that I use a DSL dialup connection with a dynamically
assigned IP from the t-online (deutsche telekom) ip adress range.
What I suspect is that it is either some kind of dns issue (I am using
dyndns to get a fixed name assigned each time I dial in and use this
name as my qmail hostname). So resolving myhost.dyndns.org works, but if
you lookup that IP then you get another hostname of course. So they
could deny it for this reason.
The other possibility could be that t-online is denying access to their
mail servers from within their own dialup IP range to keep people from
using their own smtp servers for various reasons ....

Unfortunatly I could not test if I can telnet to a t-online mail server
from an other (non t-online) dialup account (Maybe somebody could
quickly do so), but I guess that should work.
Now to resolve this issue:
Is it possible somehow to tell qmail to use a specific relay server when
sending out messages to a special (in my case, a t-online) recipient,
because there is an smtp server of my dialup provider which (when used
as my outgoing smtp server) works for sending mail to t-online adresses?


Thanks for any answer

Regards
Florian