Allocated and Consumed Resources

If you are subscribed to a number of service plans at once, then you
have several subscriptions. For each subscription, the following types
of allocated resources are listed in Plesk at the Account section >
Resources:

• Disk space. This is the total amount of disk space allocated to
  your account with subscription. This amount includes all data related
  to your websites, email accounts, applications, backups, and log
  files.

• Traffic. This is the total amount of data in megabytes that can
  be transferred monthly from all your websites.

• Domains. This is the number of websites that can have separate
  second-level domain names, such as, for example, example.com.

  For information about setting up websites, refer to the sections Set
  Up Your First Website and Adding
  Domains.

• Subdomains. This is the number of additional websites that can
  have third-level domain names, such as, for example,
  news.example.com.

  For information about setting up subdomains, refer to the section
  Adding Subdomains.

• Domain aliases. This is the number of additional domain names
  that can be set up to point to one of your sites. For example,
  example.fr and example.de can both point to example.com.

  For information about setting up domain aliases, refer to the section
  Adding Domain Aliases.

• Mailboxes. This is the number of mailboxes that can be created
  under all your websites.

  For information about creating mailboxes, refer to the chapter
  Mail.

• Mailbox size. This is the amount of disk space that can be
  occupied by a mailbox.

• Total mailboxes quota. This is the total amount of disk space
  that can be used by all mailboxes under all your domains. This option
  is available only on Windows-based customer accounts.

• Mailing lists. This is the total number of mailing lists that can
  be set up under all your websites. Note that there are mailing lists
  and mail groups, which serve the same purpose, but are slightly
  different in functionality. Mailing lists support archiving and
  pre-moderation of messages, while mail groups can only be used for
  sending one message to a number of recipients at once.

  …