1) several incoming (virtual) domains
2) some local users
3) wildcard catchall accounts to collect the emails not matching the local users
- Setup the virtual domains in the dc_other_hostnames variable in /etc/exim4/update-exim4.conf.conf. These are the domains considered local by this installation of Exim4. Any other domains will be routed as remote mail either through the IP defined by dc_smarthost, or direct delivery through DNS lookup of the MX records, or a hubbed_hosts definition file if it exists which overrides the DNS lookups.
- Create the local users with adduser
- If required, create the local user sending addresses (for the From: header) in /etc/email-addresses (otherwise the local user will be stamped with the mail hostname defined in /etc/mailname)
- #/etc/email-addresses
- user1: user1@domain1.com
- user2: user2@domain2.net
- Define the catchall accounts in a new a wildcard aliases file /etc/aliases_wildcards
- # /etc/aliases_wildcards
- #*@domain1.com: domain1-catchall-user
- #*@domain2.net: domain1-catchall-user
- Create a new router directive to process the wildcard aliases - the first 3 digits of the filename define which order routers are processed by Exim4. This needs to be after the local_user router which is by default 900 so any value higher than 900 will work. I've chosen 999. /etc/exim4/conf.d/router/999_exim4-config_system_aliases_wildcard
- # This router handles wildcard aliasing using a /etc/aliases_wildcards file
- # /etc/aliases_wildcards must exist as it is a non-standard file
- system_aliases_wildcards:
- debug_print = "R: system_aliases_wildcards for $local_part@$domain"
- driver = redirect
- domains = +local_domains
- allow_fail
- allow_defer
- data = ${lookup{*@$domain}lsearch*{/etc/aliases_wildcards}}
- file_transport = address_file
- Check the routing works as expected
- exim4 -bt user1@domain1.com
- exim4 -bt notauser@domain1.com
- The first command should show email routing to a local user using the local_user router.
- R: system_aliases for user1@domain1.com
- R: userforward for user1@domain1.com
- R: procmail for user1@domain1.com
- R: maildrop for user1@domain1.com
- R: lowuid_aliases for user1@domain1.com (UID 1001)
- R: local_user for user1@domain1.com
- user1@domain1.com
- router = local_user, transport = maildir_home
- The second command should show email routing to the catchall account again using the local_user router:
- R: system_aliases for notauser@domain1.com
- R: system_aliases_wildcards for notauser@domain1.com
- R: system_aliases for domain1-catchall-user@localsystem.com
- R: userforward for domain1-catchall-user@localsystem.com
- R: procmail for domain1-catchall-user@localsystem.com
- R: maildrop for domain1-catchall-user@localsystem.com
- R: lowuid_aliases for domain1-catchall-user@localsystem.com (UID 1000)
- R: local_user for domain1-catchall-user@localsystem.com
- domain1-catchall-user@localsystem.com
- <-- notauser@domain1.com
- router = local_user, transport = maildir_home
