Eu tive o mesmo problema, eis como era meu paniclog do exim4:
$ sudo cat /var/log/exim4/paniclog
2014-02-01 21:36:51 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
2014-02-01 22:03:33 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
2014-02-01 22:33:19 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
2014-02-01 22:36:33 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
2014-02-01 23:03:51 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
2014-02-01 23:14:31 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
2014-02-02 11:09:48 socket bind() to port 25 for address 127.0.0.1 failed: Address already in use: daemon abandoned
Este problema aparentemente foi resolvido com a exclusão do arquivo paniclog