Virtmaps - Providing E-Mail for Virtual Subhosts
In order to provide e-mail for your Virtual
Subhost customers, you will probably use the Virtual Server "virtmaps"
feature. This is a proprietary feature (only available on our Virtual
Servers) that we have added to sendmail, the underlying program
which handles all of your VPS E-Mail.
Why Virtmaps?
An HTTP/1.1 compliant web server (like your Virtual Server Apache
Web Server) can detect Virtual Subhost domains when an HTTP request
is made, and it sends back the corresponding content to the client. However,
an SMTP server without the virtmaps feature cannot detect Virtual Subhost
domains. It can only see that subhost1.com and subhost2.com resolve to
the same IP address. So, to the SMTP server, webmaster@subhost1.com and
webmaster@subhost2.com are the same webmaster.
The virtmaps feature provides your Virtual Server SMTP server a method
to detect the domain name of an incoming e-mail. Then, e-mail to similar
usernames but different domain names can be routed differently. This allows
you to configure similar domain-specific e-mail aliases (such as webmaster@subhost1.com
and webmaster@subhost2.com) and map them to different e-mail addresses.
The virtmaps feature also supports wild card mapping, so that any e-mail
sent to a non-existing e-mail address is delivered to a "catch-all" e-mail
alias or address.
It is up to you how you use the virtmaps feature to provide e-mail for
your Virtual Subhost customers. Many Virtual Server administrators provide
their Virtual Subhost customers with one E-Mail
User Account. Then they create virtmaps (often including a catch-all
virtmap as well) for the customer that map to this single POP/IMAP account.
Creating Virtmaps
There are several methods you can use to create virtmaps on your VPS
NOTE: In order for a Virtual Server to recieve e-mail for a particular domain name, that
domain name must appear on the "Cw" line in the Virtual Server ~/etc/sendmail.cf file.
If you ordered a domain name from us (in other words, the domain is being resolved by our name servers)
then we probably added it to your VPS ~/etc/sendmail.cf file for you.
- Telnet or SSH
You can create a virtmaps during a Telnet/SSH session with your VPS. Connect to your Virtual Server via
Telnet or SSH and do the following.
- Add the virtmap to your ~/etc/virtmaps file. Use an online file editor, like pico, or
transfer the file to your PC in order to add the virtmap. Be sure to download and upload the
~/etc/virtmaps file in ASCII mode.
The virtmap you create in your ~/etc/virtmaps file should look something like this:
webmaster@subhost1.com e-mail_address1
webmaster@subhost2.com e-mail_address2
subhost2.com e-mail_address3
The left hand side of the virtmap is the incoming e-mail address. The right hand side is the outgoing
e-mail address. If the left hand side is only a domain name then all e-mail sent to that domain name
will be delivered to the e-mail address on the right hand side. All e-mail is delivered to the first
virtmap that matches, if there is a virtmap that matches.
- Run the vnewvirtmaps command.
% vnewvirtmaps
Removing Virtmaps
If you wish to use Telnet or SSH,
connect to your Virtual Server via Telnet or SSH and do the following.
- Remove the virtmap from your ~/etc/virtmaps file. Use an online file editor, like pico,
or transfer the file to your PC in order to remove the virtmap. Be sure to download and upload the
~/etc/virtmaps file in ASCII mode.
- Run the vnewvirtmaps command.
% vnewvirtmaps
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