(It would have helped tremendously if you would not have left out half of the error message.)
So my guess is that it's been originally
remote_smtp defer (98): Address already in use
in which case it would mean that when exim wanted to make the connection (remote_smtp) it was unable to bind to the IP address/port it wanted to use.
This could be caused by several things:
- it may be that you force exim to bind to an address which doesn't exist on the server;
- it could be that the address is already used by a different program; or
- it is possible that the address+port is already allocated, or all ports are in use.
Generally it is advised to run a standalone exim in debug mode to see exactly what's happening. You can try to deliver a message in the queue by issuing
exim -d -M msgid | tee /tmp/exim_delivery_debug.log
and look for the specific message, and you should see exactly what address exim tries to bind to and what may cause the message. (If you specify interface in the smtp driver (remote_smtp) then try not to and see what's happening.)