[exim] All hotmail e-mail timing out

For the past 5 days, but not previously, all hotmail e-mail to a
particular exim machine has been timing out, like this (taken from the log):

SMTP data timeout (message abandoned) on connection from
bay0-omc2-s##.bay0.hotmail.com [65.54.246.###] F=<[someone]@hotmail.com>

I've replaced the local parts with [someone] and some digits in the
hostname/IP address with ##, but the rest is pretty much the same for
all the timeouts.

All other e-mail seems to arrive OK, though there are other occasional
timeouts, but precisely zero deliveries from hotmail servers.

I've put smtp_receive_timeout up to 8m, but that hasn't helped.

Does anyone know what I can do about it?

Further information that might be significant:

- The server in question is a home machine behind an adsl line with a
static ip address.

- Another (work) server I look after is receiving hotmail e-mail fine.

- I changed my adsl router recently, and possibly the change coincided
with the start of the timeouts. Though quite why that would affect only
hotmail I don't know. The idea was to make the network less flaky, not more.

Any ideas appreciated.

Thanks,

Chris

$ exim -bV
Exim version 4.63 #1 built 06-Dec-2006 17:22:51
$ uname -ovr
2.6.20-4-386 #2 Fri Jan 5 04:27:14 UTC 2007 GNU/Linux