How do quotas work on mailboxes?

Issue

How do quotas work for users' mailboxes?

Solution

The Mirapoint appliance lets the administrator set a quota and quota policy for each IMAP user. When a user has mail exceeding the 90% of the allotted disk space, they receive an IMAP warning message each time they connect to the IMAP server. When the user exceeds their quota, the quota policy set by the system administrator determines how the over-quota messages are handled. Quota policy settings are as follows:

• Queue - Where over-quota messages are denied, and placed in a queue for later delivery. Redelivery is attempted until the user has deleted enough messages from their mailbox or subfolders. This is the default setting.
• Reject - Where over-quota messages are bounced and never reach a mailbox.
• Allowinbox - Where over-quota messages are added to a user inbox even if the inbox is over quota. If a message is sent to an over-quota subfolder, the message gets delivered to the inbox instead.

When the quota is set to the default Queue, users generally have 5 days to clear space off the server, as messages queue on sending servers for reattempted delivery for 5 days.

When the quota policy is set to Allowinbox mail is delivered to the inbox, and users can read and forward mail, but they are not able to refile messages in subfolders, nor is a copy of the forwarded message placed in the Sent folder until enough messages have been deleted from their inbox or subfolders to lower the quota again.

If a user creates a folder subordinate to their mailbox, the administrator can set a separate quota for the subfolder.

If no quota is assigned it is considered part of the top level mailbox's quota.

If a quota is set by the administrator the quota is separate and independent of any other quotas set on higher level folders.

For more information, see the Mirapoint Administration Protocol Reference.