Mailbox sizing

[taeandji]

It sounds a stupid question but I gotta ask you guys.
we are using exchange 5.5 right now that has about 12GB in D drive for exchange and have about 100 mailboxes. However, the available HDD space is 1.8GB left. We used 10GB in 2 years. So, now mailbox sizing strategy is becoming a issue in our company. Currently, regular employee has 50MB and managers have 75MB limit and Executives have 100MB mailbox limit. I did simple math to calculate these
10 executives * 100MB = 1GB
10 Managers * 75MB = 750MB
80 Users * 50 MB = 4GB
Publick Folder = 700 MB
So, it should be closed to less than 7GB!!!
Also, there should be some log files but it shouldn't be occupied to 11GB right now!!!
Can anybody let me know what else will cause the HDD size and what should be the correct sizing strategy?

 

[Killman]

Were these limits set after the you reached 1.8GB?
Is limit set to Prohibit send and receive?

 

[taeandji]

Those numbers were set for Prohibit to send and receive and it was set before it reached to 1.8GB Before, I saw that one of log file was 5GB but I enabled the circular logging so, it is just overwritting one over. Thanks.