Dear Support,Yesterday we encountered an error on our Exchange server after we disabled an AD account. The account is a meeting room which is no longer used. The account existed so we could book the room using the calendar. Immediately after the account was disabled, it caused many of our clients in our branch office to "Offline mode". New emails were not sent to the clients. The following errors were repeated every 3 minutes. It was solved when we re-enabled the account. I understand that event ID 9548 is resolved with the following link, but it doesn't mention about client connectivity. Please can you investigate further?http://support.microsoft.com/default.aspx/kb/278966/en-usMany ThanksDjangoProblem #1 Event Type: Error Event Source: MSExchangeIS Mailbox Store Event Category: Logons Event ID: 1022 Date: 2/12/2007 Time: 5:18:27 PM User: N/A Computer: EXS-MGMPL Description: Logon Failure on database "First Storage Group\Mailbox Store (<server name>)" - Windows 2000 account <account name>; mailbox /o=First Organization/ou=First Administrative Group/cn=Recipients/cn=<resource name>. Error: -2147221231 Problem #2 Event Type: Warning Event Source: MSExchangeIS Event Category: General Event ID: 9548 Date: 2/12/2007 Time: 5:18:27 PM User: N/A Computer: EXS-MGMPL Description: Disabled user /o=First Organization/ou=First Administrative Group/cn=Recipients/cn=room.a does not have a master account SID. Please use Active Directory MMC to set an active account as this user's master account.