Hi All,

I came across this problem recently…  A user had hit their Send Quota limit on their mailbox and was unable to send any emails (and refused to clean up their mailbox).  So being the nice sys admin I am I upped their send limit and sent them away with the standard give that 15 mins, and retry…  15 mins later they were back at my desk still unable to send.

I always knew that quota changes wouldn’t take effect straight away but I didn’t know how long it was before it did, and past experience told me it seemed to vary.  So I decided I’d find out once and for all and came across this technet article that explains how long it takes, why, and how to reduce it if you want. 

By default (for Exchange 2007) it can take up to 2 hours for the change to be picked up by Exchange.  The information store (IS) service is responsible for enforcing mailbox size limits and uses a mailbox information cache to hold data on the mailbox including quota limits.  The IS refreshes this cache every 2 hours… So worse case the IS may have just carried out a refresh before you adjusted the mailbox limits and you’re set for a 2 hour wait.  Of course you may get lucky and the refresh could occur just a few minutes after you adjust the limit.

Adjusting the refresh period involves creating some registry keys and restarting the Exchange IS service (which will disconnect clients from their mailboxes).  Full details are given in the technet article but to summarise… 

  1. Load regedit (running as a user with Exchange Server Admin rights and Admin rights on the server).
  2. Go to HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
  3. Create a new DWORD value “Reread Logon Quotas Interval” (without the quotes) and give it a decimal value of 1200 (that’s 20 minutes in seconds)
  4. Still under the key ParametersSystem create a new DWORD value “Mailbox Cache Age Limit” and give it a decimal value of 20.  It makes sense to keep this age limit the same as the refresh interval in point 3 above.
  5. Restart the Exchange IS.


The technet article has an additional step of creating a registry key for adjusting the expiration interval for user object data, however this by default is 5 minutes which I think is short enough and the article states reducing this may impact Exchange server performance. 

Hope you find this useful, I’d recommend only changing the interval if you find you’re frequently having to increase mailbox quotas!!