Complete Virtual Mail Server/Linux vmail user

The vmail user
Because valid UNIX user and group id's are needed to store the mailboxes, those should be created as well.
 * Most services get a system ID under 1000.
 * In Gentoo the user ID's start at 1000.
 * An ID of 5000 is chosen for the vmail user.

If there are hundreds of shell users on the system a different ID can be used as well. For the vmail group the same is done. This will not be a shell account for anybody to log in with.

Storage space
Next to think about is the mail storage. This can be a partition, an NFS share or any ordinary sub-directory. Here is chosen as noted above and created as a 32GiB raid10 partition. Wherever it is chosen to be stored, ownership should be changed appropriately.

Also permissions should be set up properly:

Check the permissions to make sure that there will not be any permission error later:

Vmail user and Postfix
Postfix needs to know where and under what ownership to store mail.