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The Outlook Calendar fully integrates with email, contacts, and other features. This integration makes the Calendar component one of the most popular features of Outlook. In this article, we will guide you through the use of the Calendars various functions. In addition, we’ll introduce you to calendar improvements that are specifically targeted to make your experience more consistent.

Working in a manager/delegate scenario

If your organization allows it, configure Outlook to connect to your Exchange mailbox using Cached Exchange Mode. This provides the best performance.

Newer versions of Microsoft Outlook, Microsoft Entourage, Outlook for iOS, Outlook for Android, and Microsoft Outlook for Mac include many improvements to the delegate feature. For more information about these versions, see:

Outlook delegate feature in mixed versions of Microsoft Outlook and Entourage

For new model sharing scenarios (REST) it is recommended to us the simplified permissions levels (can edit, can view titles and locations, etc.) rather than customizing permissions for delegates.  Custom permission levels are not supported in new model sharing and can lead to unexpected results. 

Limit the number of delegates

Outlook does not limit the number of delegates that you can add. However, we recommend that you only grant Editor permissions to one (1) delegate. This allows you to track when and how a meeting was processed. Considering the fact that a delegate can use multiple devices to access your data, having many delegates with Editor permissions makes it very difficult to determine why meetings are missing or out of date.

Even if you only grant Editor permissions to one delegate, avoid adding a large number of delegates with Reviewer or Contributor permissions. This is because adding large numbers of delegates may exhaust other resources. For example, the size limit for rule data may be reached. When you add a delegate, various changes take place:

  • Outlook applies permissions to relevant folders.

  • The PublicDelegates Active Directory attribute is updated to add "Send on Behalf of" permissions to the delegate.

  • Outlook adds the delegate to a forward rule on the manager's mailbox. This forwards meeting requests to the delegate.

  • Outlook saves additional delegate information in the manager's mailbox.

Each of these component areas may have different limits. Nearing these limits can affect performance and stability.


  • During development and testing of the product, Microsoft used a maximum of four (4) delegates. Additionally, the delegates only used Outlook. Devices were not included in the testing.

  • If the delegate with Editor permissions must be replaced either temporarily or indefinitely, change the permissions from Editor to Reviewer or none. Then, grant Editor permissions to the new or backup delegate.

Working with recurring meetings

Set end dates and limit the number of occurrences

Outlook makes it easy to schedule a meeting that has multiple regular occurrences. We recommend that you always set an end date and limit the recurring series to a specific number of occurrences. Most likely, recurring meetings will require modifications at some point. For example, attendees will be added to or removed from a single occurrence, or the meeting location or time will change due to vacation dates or unforeseen circumstances. Outlook saves each of these unique changes as a meeting exception. Meetings with a very large number of exceptions result in a meeting series that is difficult to manage. Additionally, it can introduce unexpected behavior. You can always create a new meeting series when the current one ends. When thinking about the number of occurrences, consider the frequency. In the period of a year, a twice weekly meeting will have about 90 more occurrences than a monthly meeting during that same period. 

End a recurring meeting before the original end date

Although you can cancel a recurring meeting, a better option is to change the end date for the series. This allows you and the attendees to keep a record of the meetings that occurred in the past. If you cancel the recurring meeting altogether, that history is lost. The best option is to set a new end date and then send the update to all attendees. This ends the meeting series early, while keeping a record of previous meetings.


  • If you end the meeting series early, exceptions associated with the recurring meeting are lost. To learn more about exceptions, see “Set end dates and limit the number of occurrences” above.

  • This best practice also applies when you need to change the Subject of an existing meeting series. End the meeting series early and create a new recurring meeting using a different Subject.

For more information about cancelling all future meetings in a series, see: Cancel all future meetings in a series

Change the organizer

Outlook does not provide a way to change a meeting organizer. To change the meeting organizer of a recurring meeting, end the recurring meeting. To do this, set an earlier end date and send the update to all attendees. After you complete this step, the new organizer should create a new recurring meeting.

For more information about setting an earlier end date, see Cancel a meeting.

Avoid using a recurring meeting to share attachments

Attachments add to the complexity of recurring meeting exceptions. Each exception contains its own copy of the attachments. As exceptions are added to recurring meetings, new copies of the attachments are created. If you make changes to one set of attachments, these changes do not propagate to the other exceptions. If you require that all attendees have the most recent copy of changes for any given meeting it is recommended, whenever possible, to save attachments to SharePoint or to OneDrive and share with a link.

Note: The actions of adding and removing attachments to standalone, non-recurring meetings are fully supported. 

Process all meeting requests and cancellations

Although you can delete a meeting request directly from your Inbox, you should properly process the meeting request by either accepting or declining it. Always use the Remove from Calendar command to process meeting cancellations from your Inbox. Avoid processing meetings directly from the Calendar module.

Avoid copying meetings

By design, Outlook removes any links between a copied meeting and the original meeting. This helps prevent inconsistencies. Newer versions of Outlook add the text string "Copy:" to the subject. This makes it easy to identify meeting copies.

Beginning in Outlook Version 2311 copying meetings is no longer supported. This is an intentional change to prevent copying meetings. Actions related to copied meetings yield unexpected results, so we recommend avoiding copying meetings. This has been a long-standing documented best practice. To limit the unexpected results, the Outlook Team implemented blocking copying meetings.

For more information about the recent update to block copying meetings, see:

Outlook blocks copying meetings with “Copying meetings is not supported.”

Forwarding meeting requests

When you use Outlook to forward a meeting to someone who was not originally invited to the meeting, Outlook sends a meeting forward notification to the meeting organizer. When the organizer receives the meeting notification, the new attendee is added to the organizer’s meeting. If existing attendees need to know that an additional attendee was added to the meeting, then the organizer must open the meeting and send a meeting update to all of the attendees.

Note: If you want to let someone know about a meeting, but not invite them, simply drag the meeting request from your calendar to the Mail icon on the lower left side of Outlook. This opens an email with information about the meeting that you can send out. Note that this email doesn't add the recipient(s) to the meeting, and it only contains meeting information such as date, time, subject, and agenda.

For Microsoft Exchange users

Microsoft Exchange Server 2007 also introduced Meeting Forward Notifications as part of the Calendar Attendant feature. If you use Outlook to connect to a mailbox on an Exchange Server organization, meeting forward notification behavior may be subject to Exchange settings, if configured by the Exchange Administrator. For example, the Exchange Administrator can prevent meeting forward notification from being sent to remote domains.

We generally recommend that an attendee not forward a meeting if they are not in the same Exchange organization as the organizer, unless all of the following conditions are true:

  • The attendee is using Microsoft Outlook 2010 or newer.

  • The attendee’s Exchange Administrator allows meeting forward notifications to be sent to remote domains.

  • The organizer is using a Microsoft Outlook client.

In the case of an attendee who uses a non-Exchange mail system, we generally recommend not forwarding a meeting, unless all of the following conditions are true:

  • The attendee is using Microsoft Outlook 2010 or newer.

  • The organizer is using a Microsoft Outlook client.

If for any reason the organizer does not receive the meeting forward notification, the meeting attendees are not added to the organizer’s meeting. If the organizer subsequently changes the meeting and sends out an update, the update is only sent to the original invitees. The attendees who earlier received the forwarded copy of the meeting will not receive the update.

If the above limitations prevent you from successfully and consistently forwarding meeting invitations, it is best to simply ask the meeting organizer to add the desired attendees. It is important to ask the meeting organizer to add the desired attendees if you are not certain that both your and the desired attendees’ environments meet the above conditions.

Note: Outlook Delegates do not receive Meeting Forward Notifications.

Additional recommendations for Microsoft Exchange users

Maintain devices that connect to your calendar

Make sure that any device that connects to your Calendar has all of the latest updates installed. Some devices use Exchange ActiveSync to synchronize the Calendar and other folders. These devices include Outlook for iOS, Outlook for Android, Apple iOS, and Android devices. Research In Motion (RIM) BlackBerry devices and others can also synchronize with the Calendar.

For more information about some of the known issues, see: Current issues with Microsoft Exchange ActiveSync and third-party devices.

Note: In some cases, multiple Outlook clients and devices may modify items at the same time, which can introduce conflicts. To minimize the likelihood, do not process the same item on two or more clients or devices within a relatively short period of time.

Maintain add-ins that integrate with Outlook

Most, if not all, Outlook add-ins access Outlook data. An add-in may change an Outlook item that you are editing at the same time, whether in Outlook or on another device. This can introduce conflicts. To minimize the likelihood, make sure to install the latest updates for any add-ins or programs that integrate with Outlook. Uninstall or disable any of these programs and add-ins that you do not use or that do not need to integrate with Outlook.

Note: In some cases, multiple Outlook clients and devices may modify items at the same time, which can introduce conflicts. To minimize the likelihood, do not process the same item on two or more clients or devices within a relatively short period of time.

See also

About the Microsoft Support and Recovery Assistant

Information about the Calendar Checking Tool for Outlook (CalCheck)

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