vestacp-docker/vesta/etc/exim4/conf.d/router/850_exim4-config_lowuid

### router/850_exim4-config_lowuid
#################################

.ifndef FIRST_USER_ACCOUNT_UID
FIRST_USER_ACCOUNT_UID = 0
.endif

.ifndef DEFAULT_SYSTEM_ACCOUNT_ALIAS
DEFAULT_SYSTEM_ACCOUNT_ALIAS = :fail: no mail to system accounts
.endif

COND_SYSTEM_USER_AND_REMOTE_SUBMITTER = "\
               ${if and{{! match_ip{$sender_host_address}{:@[]}}\
                        {<{$local_user_uid}{FIRST_USER_ACCOUNT_UID}}}\
                    {1}{0}\
		}"

lowuid_aliases:
  debug_print = "R: lowuid_aliases for $local_part@$domain (UID $local_user_uid)"
  check_local_user
  driver = redirect
  allow_fail
  domains = +local_domains
  condition = COND_SYSTEM_USER_AND_REMOTE_SUBMITTER
  data = ${if exists{CONFDIR/lowuid-aliases}\
              {${lookup{$local_part}lsearch{CONFDIR/lowuid-aliases}\
              {$value}{DEFAULT_SYSTEM_ACCOUNT_ALIAS}}}\
              {DEFAULT_SYSTEM_ACCOUNT_ALIAS}}