[Exim] Sending mails from exim to servers with IP addresses …

People using exim 3.x are trying to mail us, but fails. Our server has an
IPaddress starting with "80.x.x.x".

I spoke with these guys, and they told me of other domains, to where they
could not mail either.

All those domains are hosted on domains starting with "80.x.x.x"

Trying to telnet on port 25 from the box on where exim is to the servers
gets a "connection timed out" - or the like.

When mailing from the system, the firewall starts logging randomly port
numbers to these IP addresses starting with "80".

The "80.x.x.x" address space was previously unused on closed on some
routers.

Is this address space closed on exim - or shall I look at the problem
elsewhere?

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Regards,

Lars Bonnesen