problem with recive mail from gmx

[Jim Holland]

Hi

On Tue, 26 Sep 2006, Dörfler Andreas wrote:

> just for the archive,
> 
> disable selective acknowledgements
> 
> echo 0 > /proc/sys/net/ipv4/tcp_sack 
> 
> after some help from external we figured out the problem 
> has todo with the selective acknowledgements ( tcp ).
> after i disabled em no more gmx errors, only errors from 
> dynamic (spam)clients left, but they dont matter.
> 
> we think thats a kernel or iptablesbug in the
> suse default kernel ( linux-2.6.8-24 )

I doubt that the problem is your fault at all or that it is a problem with
the suse kernel.  Why do so many people have problems receiving mail from
this specific ISP?  According to our logs they are the worst ISP in the
world in this regard - in the category of spammers who don't follow proper
protocols.  In fact I sent off a letter of complaint to them earlier this
morning on this issue.

If you change the tcp_sack setting just for the benefit of a single broken
ISP then you are losing the benefits of that TCP option that was
especially developed to handle lossy connections.  Why not also switch off
PMTUD, for example, just because you have a client who can't connect to a
broken web server?

My vote: Let's give 'em the sack :-)

Regards

Jim Holland
System Administrator
MANGO - Zimbabwe's non-profit e-mail service