How to setup virtual users on Open WebMail using Postfix & vm-pop3d
Written by Kevin L. Ellis
This tutorial will show you how to setup Open WebMail (OWM) so that you can have both real users and pure virtual users access mail by either pop3 (i.e. Netscape, etc) or by using a web interface (Open WebMail). A "pure" virtual user to me is one that does not have an account on the machine, there is no entry in /etc/passwd for them. They only exist to the e-mail system. You will be able to setup virtual users for both the main domain of the box and virtual domains that the box hosts. You will also be able to use the same user name for different domains, there are no limitations with user names.
Get down Open WebMail, Postfix, and vm-pop3d and install them all. Read through how vm-pop3d works so you have a general understanding of how it's able to service virtual users. Get all these working together before you proceed any further.
We are going to configure OWM to use the standard unix authentication, so we need to setup auth_unix.pl to point to our passwd file. For me this is /etc/passwd and /etc/shadow, your system may vary.
Next we need to setup auth_pop3.pl. This authentication module will be used for virtual users and users to virtual domains. Make the appropriate changes to $pop3_authserver, $pop3_authport, and $local_uid.
Now we need to make changes to openwebmail.conf. Setup mailspooldir to point to your normal mail spool directory. For me this is /var/spool/mail. This is the spool that actual users get their mail delivered to. We also want to setup OWM to use unix style authentication, so set auth_module to auth_unix.pl.
mailspooldir /var/spool/mail.
auth_module auth_unix.pl.
Also add these configurations to openwebmail.conf:
use_homedirspools no
use_homedirfolders no
enable_changepwd no
enable_autoreply no
enable_setforward no
enable_setfromemail no
getmail_from_pop3_authserver no
autopop3_at_refresh yes
auth_withdomain no
This will configure OWM so that real users will be able to access either regular e-mail using Open WebMail without having to do anything special. When a real user of the system logs in using just their user name (e.g. john), then OWM will authenticate that user using the systems passwd file.
Virtual users must be setup and created before they will work.
Step 1
If this virtual user is at a virtual domain your machine is hosting, then add a mapping for the user in /etc/postfix/virtual.cf. The lines you will add will look something like this:
virtualdomain anything
username@virtualdomain uname.virtualdomain
The first line only needs to be done once per virtual domain name.
Example:
virtualcompany.com anything
john@virtualcompany.com john.virtualcompany.com
This will map any incoming mail to john@virtualcompany.com to a user named john.virtualcompany.com. Once you've added this run the command 'postmap /etc/postfix/virtual.cf' to update the virtual table.
Note: if this is a virtual user to the main domain of the machine, you don't have to add an entry to virtual.cf.
Step 2
Add a local alias to /etc/aliases for this user. If this is a virtual user to the domain of the host machine, then you'll add a line like this:
username: /var/spool/virtual/domain/name
For example, if you are adding a virtual user (joe) for the domain of the machine (widgets.com), you'd add:
joe: /var/spool/virtual/widgets.com/joe
On the other hand, if it's to a virtual domain, then the uname should be the uname.domain and 'domain' will be that virtual domain. Continuing the example in step 1, we'd add:
john.virtualcompany.com: /var/spool/virtual/virtualcompany.com/john
After that we need to update Postfix's alias database, so run the command 'postalias /etc/aliases'.
Step 1 tell postfix that mail directed to john@virtualcompany.com should first be mapped to a user named john.virtualcompany.com and step 2 tells postfix to then place that users mail in the mail spool file /var/spool/virtual/virtualcompany.com/john
Step 3
Now we need to make a mail spool directory for it. Make a directory in /var/spool/virtual with the name of the domain.
For our virtual user joe at the main domain of the host machine, we'd do:
mkdir /var/spool/virtual/widgets.com
For our virtual user john at the virtual domain , we'd do:
mkdir /var/spool/virtual/virtualcompany.com
Once that's done we need to execute these two commands:
chown root.mail /var/spool/virtual/domain
chmod og+wt /var/spool/virtual/domain
For our example we started in step 1, we'd execute:
mkdir /var/spool/virtual/virtualcompany.com
chown root.mail /var/spool/virtual/virtualcompany.com
chmod og+wt /var/spool/virtual/virtualcompany.com
If this mail spool directory already exists we can skip this step. Thus, once you perform this step for one virtual user at this domain, any other virtual users at this domain you create you don't have to do this.
Step 4
Now we need to configure OWM for virtual users at these domains using Open WebMail's per site configuration feature. Go to /usr/local/apache/cgi-bin/openwebmail/etc/sites.conf (or to your Open WebMail location) and make a new file named 'domain', then add these lines:
mailspooldir /var/spool/virtual/DOMAIN
auth_withdomain yes
auth_module auth_pop3.pl
domainnames DOMAIN
For our virtual user joe at widgets.com we'd create a text file called widgets.com containing:
mailspooldir /var/spool/virtual/widgets.com
auth_withdomain yes
auth_module auth_pop3.pl
domainnames widgets.com
And for john at virtualcompany.com, create a text file called virtualcompany.com containing:
mailspooldir /var/spool/virtual/virtualcompany.com
auth_withdomain yes
auth_module auth_pop3.pl
domainnames virtualcompany.com
This will configure OWM so that when a virtual user logs in using their full e-mail address (e.g. john@virtualcompany.com, or joe@widgets.com), OWM will use the configuration file for that domain (i.e. virtualcompany.com or widgets.com). The config file for these sites will tell OWM to authenticate the user using pop3 (vm-pop3d). The full address will be sent to vm-pop3d which will then authenticate this user using the virtual passwd for this domain.
Step 5
We need to make a directory in /etc/virtual to hold the password file for this domain. This is the directory that vm-pop3d looks in when it authenticates a user. So we'd do this:
mkdir /etc/virtual/domain
For our user joe, we'd execute:
mkdir /etc/virtual/widgets.com
For our user john, we'd execute:
mkdir /etc/virtual/virtualcompany.com
Step 6
Now we need to create a password for this user. Using the addpasswd script laid out on the vm-pop3d homepage, we'd execute this command:
addpasswd uname password >> /etc/virtual/domain/passwd
For our example, if user john wanted the password 'turtle', we'd execute:
addpasswd john turtle >> /etc/virtual/virtualcompany.com/passwd
Conclusion
And that's it! A real user with an e-mail account at the domain of the machine can log into Open WebMail by just putting in their user name in the login screen. A virtual user needs to put in their full e-mail address (i.e. uname@domain).
For pop3 mail retrieval, a real user would send just their user name to the pop3 server, a virtual user would send their full e-mail address (in either the form 'username:domain" or 'username@domain').
Last modified: September 7st, 2002
