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Microsoft 365 - Exchange Online Calendaring Best Practices

Microsoft Exchange Online, which serves as the default email and calendaring solution for all CU Boulder faculty and staff, provides a robust email management and calendaring platform. Many throughout CU Boulder rely on their Exchange Online calendar to help track where they need to be and who they will interact with. So making sure everyone's calendars remain accurate and up to date has become a critical need for many faculty and staff. There are different approaches and email/calendar clients available to manage Exchange Online calendars, but not all are equally suited or reliable.

This “Best Practice” guide provides guidance to Exchange Online calendar users on the practices and email/calendar clients that best avoid calendaring problems. They have been collected from many years of experience with Exchange and from multiple sources.

Table of Contents

General Calendaring Best Practices

For most Exchange Online calendar users, the service and their chosen client(s) work reliably. Users who do not require complicated calendaring functionality will rarely if ever experience issues. In these more basic calendaring situations, where someone only has a handful of appointments each week and manages all of the details themselves, these best practices may not be required unless noticeable issues, such as inconsistent/inaccurate meeting information, disappearing meetings, or differences between desktop and mobile clients, occur.

For users who do require complicated calendaring, particularly those who schedule numerous meetings with many attendees or those who have delegated access to create and edit meetings on behalf of another individual, following these “Best Practices” becomes far more critical. Following these steps will lead to improved stability, predictability, collaboration, and reduce frustration and functionality issues.

Preferred Clients

The most current version of Microsoft Outlook for all platforms, including mobile devices, will provide the most robust and reliable calendaring experience.

  • Microsoft Outlook desktop clients are available for both Windows and Macintosh operating systems.
  • Microsoft Outlook mobile clients are available through the Apple App Store for iPhones or iPad or from the Google Play Store for Android phones or tablets.

In general, it is best to use mobile devices for “read-only” access. To the extent possible, create, edit, and reply to meetings from a desktop Microsoft Outlook client only. Although creating and editing meetings from a mobile device will work, managing your calendar from a mobile device is one of the most common sources of calendaring problems.

Scheduling Appointments

Exchange Online provides convenient and powerful collaboration abilities by allowing people to view the free/busy time of other users and/or resources (such as conference room or equipment), send meeting requests that will appear on each user's calendar, and track responses for who can/cannot attend the meeting. Reliably scheduling meetings with other attendees and resources requires understanding an important detail about how Exchange Online Calendaring operates: each user maintains their own copy of the meeting.

There's a common misunderstanding about how Exchange Online Calendaring operates. Many people assume that the calendar system tracks a meeting as a single copy and that any edits to a meeting will automatically update and appear for all attendees. Instead, in order to allow Exchange Online Calendaring meetings to interoperate with other calendaring systems and external users, all calendaring data requires the sending and receiving of email messages to all attendees. As each attendee receives an email message with calendar appointment information, their email and calendaring client reads the message and updates their individual copy of the meeting on their personal calendar.

Understanding this operational detail leads to several important “Best Practices” for scheduling appointments with others: 

Creating and Editing Meetings

  • If you edit a meeting (changing the date/time, changing the subject, changing the location, changing the details, or adding/removing attendees) the email and calendar client will often ask if you want to send an email to the attendees. If you want anyone else to see your edits, you need to send the email. The general “best practice” is to always send the email to make sure everyone in the meeting sees the most current details for the meeting. 

Responding to Meeting Requests

  • Always send a response to the meeting organizer when you accept or decline. Some email/calendar clients give you the option to not send a response, but doing this will make it look like you are not attending the meeting and is very unhelpful to the meeting organizer.

Scheduling Resources (Rooms or Equipment)

  • Do not use the option of directly proposing a meeting to a resource (meeting room) calendar. Instead, invite the resource to the meeting via the "Rooms" button or add the room name as one of the invitees to the meeting. Check the scheduling assistant to be sure the resource is available, then send the invitation. Make sure you get an acknowledgment from the resource that it has been accepted. Follow this path to reliably reserve rooms for your meeting.

Recurring Meetings

  • Only use the recurring meeting feature if the time and place are the same each week.
  • Always set an end date and limit the recurring series to a specific number of occurrences. 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. Microsoft recommends setting the end date no more than 6 months.
  • Although you can cancel a recurring meeting, a better option is to change the end date for the series. This allows 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.

Delegated Calendaring Best Practices 

One of the advanced features of Exchange Online Calendaring allows users to delegate the ability to create and edit their meetings to another individual, usually a personal or departmental administrative assistant. Using the delegated calendaring feature, however, increases the potential for calendaring problems. Individuals who need delegated calendaring usually have the greatest need for accurate calendaring: they often are scheduled in dozens of meetings every week and rely upon their calendar to keep them on track.

Due to these complexities, if you grant another individual the ability to edit your calendar (whether the “Editor”, “Author” or any other permissions level), it is vital that both you and the person who receives the delegated permissions stick to the General Calendaring and Appointment Scheduling Best Practices outlined above, as well as:

Assigning Delegate Access

  • Limit to 1 Delegate if Possible: Outlook does not limit the number of delegates that you can add. However, we recommend that you only grant Editor permissions to one delegate. This allows you to track when and how a meeting was processed. Considering 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.

Configuring Delegate Client Environments

  • Everyone involved in the Calendaring process should be using the same platform (Windows or Mac) and the most up to date Microsoft Outlook versions including patch levels. That said, asking people to change their platform and client can disrupt their productivity. For example, if someone who has been a Mac user for many years is asked to adopt and learn Windows instead it will take them time to learn and adjust. Consolidating around a consistent platform is a best practice and important consideration, but may only be necessary as a last resort if all of the other best practices fail to resolve calendaring issues.
  • Mobile devices create the most problems: they are best used for reference only. You can set up personal appointments on a mobile phone, but try to propose or accept meeting invitations on your computer only. In general, the more complicated or more detailed the task, the more important it is for you to use Outlook (for Windows or Mac) or Outlook on the web.
  • Do not auto-accept requests. If a user has granted one or more persons delegate access to their calendar, or if a user is a delegate, turn off automatic acceptance of meeting requests. By turning off automatic acceptance, problems are avoided with delegate workflow.
  • If you have a delegate manage your calendar, do it consistently. If your delegate creates and accepts meetings for you, always do it the same way. This leads to more consistent, predictable scheduling.


Interested in more information? There are many in-depth and well-written discussions on the causes of and solutions for Exchange calendaring issues: