Vpopmail is a set of programs for creating and managingmultiple virtual domains on a qmail server.It is geared toward ease of use for system administrators as well as security and efficency. With the associated command line programs,system administrators never need touch any of the underlying qmail files and processes. All details are automatically handled. -------------------------------------------------------------------------- Features include   * Support for 1 to 23 million virtual email domains using a     "grow as it goes" balenced directory tree.   * Support for 1 to 23 million email users per domain using the     same balenced tree structure.   * Automates all qmail configurations into handy and scriptable    command line programs and documented API library calls.   * Automates Unix user/group/other permissioning of directories    and files.   * Supports authenticated relay control of your qmail smtp server.   * Virtual email file/directories can be assigned to any user/group    or do the default vpopmail/vchkpw 89/89.   * Does not require email user accounts in /etc/passwd   * Supports name or IP based virtual domains   * Optionally automates support for:       * Storing clear text passwords to help tech support workers       * Record last authentication and automates deletion of        stale accounts.       * Storing alias/forwards in mysql or oracle   * Configurable logging based on real world admin's comments    and requirements.   * Support for MySQL, Oracle, PostgreSQL, /etc/passwd, /etc/shadow,     LDAP, Sybase, and default cdb authentication storage.   * Delivers directly to Maildir for use with qmail-pop3d,    .qmail files or any other Maildir program.   * No need to have hundreds of .qmail files for virtual domains.    Each domain gets it's own directory under vpopmail user with a    separate password file for each domain.   * Documented C library for all vpopmail features and transactions. --------------------------------------------------------------------------Latest versions of vpopmail are available fromhttp://sourceforge.net/projects/vpopmail--------------------------------------------------------------------------For general installation instructions see INSTALL fileFor people upgrading please read UPGRADE--------------------------------------------------------------------------By default, vpopmail stores all the account configuration and settingsin CDB files. CDB is a fast, reliable & simple database package that waswritten by Dan Bernstein (the author of qmail). CDB is a good choicefor small vpopmail sites, but if you are running a larger server,there are other authentication modules available that can help increaseperformance or improve managability :  For help with mysql see README.mysql  For help with postgres see README.pgsql  For help with LDAP see README.ldap  For help with oracle see README.oracle  For help with sybase see README.sybase--------------------------------------------------------------------------Qmail and Virtual domainsQmail has an idea of email domains that are "local" and "virtual". Localdomains are ones which primarily match against /etc/passwd. Virtual domainsmatch against domains listed in the qmail control file "virtualdomains".Vpopmail makes use of the qmail users/assign file and virtualdomains file.The users/assign file gets compiled into a users/cdb file. It is a hasheddatabase to speed searches for patterns. If a pattern is matched then qmaildelivers the email to the directory defined in the file using the uid andgid which as also defined. Vpopmail makes use of this method to have qmaildeliver all virtual domain email as the single uid/gid vpopmail/vchkpw.It also uses it to direct delivery to a vpopmail/domains/<virtualdomain>directory.Once qmail-local gets the information from the users/assign file it performsstandard .qmail file processing in the directory. Normal .qmail-<user> files can be used for forwarding, aliases or invoking programs such as ezmlm.If no matches are found qmail-local looks for a .qmail-default file. This isthe last stage in qmail-locals delivery mechansim. Vpopmail uses this file to invoke the vdelivermail program. This program takes two parameters, the first is not used (it is there for backward compatibility). The second parameter is the default delivery if a virtual domain user can not be found. Basically, it can be a directory to deliver the email to, an email address toforward the email to or the string "bounce-no-mailbox" to bounce the mail back to the sender.Once vdelivermail is started up, it uses the core vpopmail api calls to check for a virtual domain user. If the user exists, the email is delivered into their directory. If vpopmail was configured for hard quotas (default is yes with 50Meg quota), then the size of the users current email files in their Maildir/new and Maildir/cur directories are counted. If the user is over quota the email is bounced back to the user with a bounce message that can be customized. If the message is 1Kbytes or smaller the email will always be delivered. This is so system administration programs can always get a message through to the user. --------------------------------------------------------------------------Directory structureOverall vpopmail directory structureVpopmail gets it's own home directory. Under this directory there are the following:  bin - contains all the binaries  lib - contains the libvpopmail.a file  include - contains the C header files  users - for backward compatibility for people who mix /etc/passwd users   with vpopmail users in one domain  domains - where all the virtual domains are kept.Virtual domain user directory structureVpopmail uses an adaptive directory structure based on a state file ".dir-control" which is automatically managed by the core vpopmail api functions "vadduser" and "vdeluser". For sites with 100 users or less, all user directories are stored in the virtual domain directory. For sites that go above 100 users the adaptive directory structure goes into effect. The basic idea is to break up the user Maildir directories across multple directories and sub directories so that there are never more than 100 user directories in a single directory.The default directory setup allows for 62 directories in 3 levels and 100 user directories per directory. The total number of user directories is equal to 100 + (62 * 100) + (62 * 62 * 100) + (62 * 62 * 62 * 100) = over 24 million directories. This should be more than sufficent for any site and probably goes beyond the technology of directory structures. If you are going to be storing large numbers of user directories, makesure you set your file system to have a higher than normal percentage of inodes. Vpopmail will automatically create these directories and sub directories as needed and populate each directory with up to 100 user accounts. As soon as a directory reaches 100 users it will create the next directory or sub directory and store the new users directory there. Look in the source code release directory contrib/ for a contributed directory reorganization program--------------------------------------------------------------------------Converting current user accountsThe vconvert program can convert email accounts from one format intoanother format. Conversion can be between /etc/passwd, vpasswd files,mysql (small version) and mysql (large version).Most current vpopmail users would probably be interested in how toconvert current domains into mysql domains. To make it simple to convertan entire machine to mysql, use the following command: vconvert -c -sThis will go through all the domains in ~vpopmail/domains directoryand read each vpasswd file and load the contents into thevpopmail.vpopmail mysql table. The vpasswd file is left untouchedfor safety. Vconvert can also be run against one or more domains at atime. This is done by running the command as so:vconvert \c \s domain1 domain2 ...To convert all users (except root and system accounts) into a mysqldomain run the following command: vconvert -e -s domain. This readsall /etc/passwd accounts and creates mysql entries using theirpasswords. The passwords can be in either /etc/passwd or /etc/shadow.These passwords should work under vchkpw authentication program.--------------------------------------------------------------------------Security and pop server under tcpserverIf all of your pop email accounts are under virtual domains, you canincrease the security of your pop server by running it under the uidand gid of vpopmail/vchkpw using the tcpserver -u and -g options.