Overgang het net naar KPN

Na mijn automatische overgang van het net naar KPN ontvang ik steeds onderstaand mail van de 'system administrator' Ik heb nooit meer dan 5à 6 emails in de inbox staan en sla ze vervolgens op in mappen. Doe ik iets fout. Ter voorkoming van veel papier afdrukken wil ik graag veel e-mails met bijlagen bewaren in de mappen

Your mailbox has exceeded one or more size limits set by your administrator.
Your mailbox size is 27088 KB.
Mailbox size limits:
You will receive a warning when your mailbox reaches 26112 KB.You may not be able to send or receive new mail until you reduce your mailbox size.
To make more space available, delete any items that you are no longer using or move them to your personal folder file (.pst).
Items in all of your mailbox folders including the Deleted Items and Sent Items folders count against your size limit.
You must empty the Deleted Items folder after deleting items or the space will not be freed.
See client Help for more information.