The question of the week this week involved resource calendars not allowing meeting requests more than 180 days out.

How can I set up the resource calendar to accept my meeting request scheduled more than 180 days out? Currently, the meeting request fails with this message:

Your meeting request was declined.
This resource can only be scheduled up to 180 days in advance. The end time should fall before .

The Exchange administrator needs to change this setting for you. In Exchange 2007 and above, the admin can change it using powershell or the Exchange admin center. In Exchange 2003, the administrator will need to edit an XML file.

Exchange 2010, 2013, 2016, Office 365

In Exchange 2010 and up, the administrator can change the setting using the Set-CalendarProcessing cmdlet.

Set-CalendarProcessing -Identity "Room 1" -BookingWindowInDays <# of days>

The maximum value is 1080 days.

Exchange 2007

The command to use is
set-mailboxcalendarsettings "MailboxAlias" -BookingWindowInDays <# of days>
Example:
set-mailboxcalendarsettings "Meeting Room 1" -BookingWindowInDays 365
You can use Get-MailboxCalendarSettings to get a long list of other values supported by the calendar.
Get-MailboxCalendarSettings mailbox alias |fl
You will see a long list of the properties and their values that are associated with the resource mailbox.

Exchange 2003

In Exchange 2003, the error message is: "Your meeting request has been declined because the end date of the meeting is beyond the booking window."

On the Exchange server, there is an AutoAccept.config.xml file that contains a BookingWindowInMonths setting. The Auto Accept Agent (AAA) runs on the server and processes meeting requests that are sent to resource mailboxes.

The max value for BookingWindowInMonths is 36.

See Configuring Auto Accept Agent for more information.