$ sudo exim -bt -d+route fred@domain-a.com
Exim version 4.71 uid=0 gid=0 pid=11129 D=fbb95cfd
Berkeley DB: Berkeley DB 4.8.24: (August 14, 2009)
Support for: crypteq iconv() IPv6 GnuTLS move_frozen_messages DKIM
Lookups: lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmnz dnsdb dsearch nis nis0 passwd
Authenticators: cram_md5 plaintext
Routers: accept dnslookup ipliteral manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore autoreply lmtp pipe smtp
Fixed never_users: 0
Size of off_t: 8
GnuTLS compile-time version: 2.8.5
GnuTLS runtime version: 2.8.5
changed uid/gid: forcing real = effective
  uid=0 gid=0 pid=11129
  auxiliary group list: <none>
seeking password data for user "uucp": cache not available
getpwnam() succeeded uid=10 gid=10
configuration file is /var/lib/exim4/config.autogenerated
log selectors = 00000ffc 00612001
trusted user
admin user
seeking password data for user "mail": cache not available
getpwnam() succeeded uid=8 gid=8
user name "root" extracted from gecos field "root"
originator: uid=0 gid=0 login=root name=root
sender address = root@mydomain.com
Address testing: uid=0 gid=108 euid=0 egid=108
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Testing fred@domain-a.com
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Considering fred@domain-a.com
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
routing fred@domain-a.com
--------> domain-a_director router <--------
local_part=fred domain=domain-a.com
checking domains
search_open: dsearch "/etc/exim4/fwd_domains"
search_find: file="/etc/exim4/fwd_domains"
  key="domain-a.com" partial=-1 affix=NULL starflags=0
LRU list:
  4/etc/exim4/fwd_domains
  End
internal_search_find: file="/etc/exim4/fwd_domains"
  type=dsearch key="domain-a.com"
file lookup required for domain-a.com
  in /etc/exim4/fwd_domains
lookup yielded: domain-a.com
domain-a.com in "dsearch;/etc/exim4/fwd_domains"? yes (matched "dsearch;/etc/exim4/fwd_domains")
calling domain-a_director router
rda_interpret (string): ${lookup{$local_part}lsearch{/etc/exim4/fwd_domains/$domain}}
search_open: lsearch "/etc/exim4/fwd_domains/domain-a.com"
search_find: file="/etc/exim4/fwd_domains/domain-a.com"
  key="fred" partial=-1 affix=NULL starflags=0
LRU list:
  :/etc/exim4/fwd_domains/domain-a.com
  4/etc/exim4/fwd_domains
  End
internal_search_find: file="/etc/exim4/fwd_domains/domain-a.com"
  type=lsearch key="fred"
file lookup required for fred
  in /etc/exim4/fwd_domains/domain-a.com
lookup failed
expanded:
file is not a filter file
parse_forward_list:
domain-a_director router declined for fred@domain-a.com
"more" is false: skipping remaining routers
no more routers
fred@domain-a.com is undeliverable: Unrouteable address
search_tidyup called
>>>>>>>>>>>>>>>> Exim pid=11129 terminating with rc=2 >>>>>>>>>>>>>>>>