Basic Configuration of the IMAP and POP Server

Set Default quota size
Enter the standard amount of disk space users should have for saving mails. Specify the value in kB.
Set Limit for Quota Warning
Once the folder reaches this limit, the user is notified that the quota is nearly exhausted.
After the expiration of this period, idle IMAP and POP users will automatically be logged out.
After this amount of time has elapsed, inactive POP3 and IMAP users are logged out automatically.
Mail will be rejected immediately when the quota limit is exceeded
If a message is delivered to a user who exceeded his quota limit, the message is usually accepted and the systems tries repeatedly to deliver it for five days, if the postfix parameter maximal_queue_lifetime was not changed. If it still cannot be delivered after that time, the mail is discarded and the original sender is sent an alert message.
If, however, this value is set to Yes the mail is rejected immediately and the sender is sent an alert.
Local User for Undeliverable Mail
Usually, all mail addressed to nonexistent addresses is rejected and the sender receives a mail containing an appropriate message. If you enter the name of an existing, local user in this field, all mail addressed to invalid addresses on this server are delivered to this user. The sender is not informed. Important: Enter the name of a local user, like mailadmin, without a domain.
User Names with Dots
If you set this switch to "Off", you will no longer able to create user names containing dots. This is the case because the dot will be used as a separator between folder hierachy levels.
If set to "On", a slash is used to separate folder hierarchies, like in Linux file systems.
Alternative Name Spaces
If you set this switch to "On", folders will no longer be listed under the "INBOX" folder, but on the same level as the "INBOX".