virtusertable - Using Domain based E-mail routing
Incoming E-mail messages can be sorted based on the recipient domain name with the virtusertable utility.
Because user accounts are not directly associated with any specific domain names, a virtusertable must be used
to differentiate between recipient domain names. For example, a virtusertable mapping will allow you to direct E-mail
messages for webmaster@mydomain.name and webmaster@subhost.name to different users on your VPS2.
Configuring Virtusertable mappings
In order to create virtusertable mappings, you must first create a text file in the /etc/mail/ directory of your
server (there is a sample file in that directory named virtusertable.sample). This file will contain virtusertable
mappings.
Each entry in a virtusertable should be on a single line. The original recipient address on the left hand side, with one
or more spaces or tabs separating it from the right hand side, which contains the destination address.
The original recipient is the E-mail address that people will send messages to, and can be either a full address
(username@domain.name), or a catch all for all messages to the specified domain (@domain.name). If you want
to create multiple virtusertable entries for a single domain, make sure that you put the catch all below any other entries
for that same domain name.
The destination address should be a local user, an alias, or a remote E-mail address. You may also use a %1 to
indicate that the original user should be prepended to a catch all.
Any time you make a change to the /etc/mail/virtusertable text file, you will need to create a db file that
sendmail can read. The following command will create the /etc/mail/virtusertable.db file when run by root.
# makemap hash /etc/mail/virtusertable < /etc/mail/virtusertable
Example Virtusertable Entries
The following entry would deliver any message sent to floyd@super-host.com to the local account floydr.
floyd@super-host.com floydr
The next entry will deliver a message sent to john@super-host.com to his E-mail account with his ISP.
john@super-host.com jfranklin@my-isp.com
Any other E-mail sent to the super-host.com domain will go to Floyd's local account.
@super-host.com floydr
Anything sent to a user at funsites.com will be sent to awesome-web.com, but will not change the username
the message was originally sent to (only the domain is modified).
@funsites.com %1@awesome-web.com
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