Outlook performance issues when you have many shared folders or mailboxes open

When you start Outlook, switch folders, or synchronize email, you may experience slow performance. Additionally, when you make changes or additions to a calendar, you may receive the following error message.

You don't have permission to create an entry in this folder. Right-click the folder, then click Properties to check your permissions for the folder. See the folder owner or your administrator to change your permissions.
You have many shared folders or mailboxes, or both, open in Outlook. In the case with a shared calendar, modifications or additions are not possible until it is finished syncing updates. 

The number of shared folders and mailboxes that you can have open without issues depends on several factors including hardware, mailbox size, size of the shared folders or mailboxes, number of folders in a shared mailbox, item count in folders, and network speed. A computer that has slower hardware, a large mailbox and slow network connection may only be able to open 5 or fewer shared folders or mailboxes. However, a faster computer that has a smaller mailbox and a fast network connection may be able to open 10 or more shared folders or mailboxes.
Reduce the number of shared folders or mailboxes that you have open in Outlook.  To do this, you must first determine whether you have shared folders or shared mailboxes open.  If you have shared mailboxes open, you must also determine how they are opened, such as being opened manually as an additional mailbox or being opened because of AutoMapping.

A shared mailbox will appear below your own mailbox in the Folder Pane, as shown in this screen shot.

Screen shot showing a shared mailbox in the Folder Pane

A shared folder will appear under Shared <Folder type>, such as Shared Calendar or Shared Contacts, as shown in these screen shots.

Screen shot showing shared folders of different types

Remove a shared mailbox:

If you have a shared mailbox open in Outlook, it was either manually added under Open these additional mailboxes or it was opened automatically because of automapping. You can determine how the shared mailbox was opened and remove the shared mailbox by following the steps in the following sections.

Remove a shared mailbox that was opened as an additional mailbox manually:

  1. Click File, Account Settings, and then click Account Settings.
  2. Select the Microsoft Exchange account, and then click Change.
  3. Click More Settings.
  4. On the Advanced tab, you can view any manually added shared mailboxes under Open these additional mailboxes.
  5. Select the shared mailbox, and then click Remove.
  6. Click Yes to confirm that you want to remove the mailbox, and then click OK.
  7. Click Next, and then click Finish.
  8. Click Close on the Account Settings window.

Note: If the shared mailbox does not appear under Open these additional mailboxes, then it is likely Automapped.  To determine whether this is the case and remove the automapped mailbox from Outlook, follow these steps:

Run the Test E-mail AutoConfiguration tool to determine whether any automapped mailboxes exist:

  1. Hold the Ctrl key, and then right-click the Outlook icon in the notification area.
  2. Click Test E-mail AutoConfiguration.
  3. Enter your email address and password.
  4. Click to clear the Use Guessmart and Secure Guessmart Authentication options.
  5. Click Test.
  6. When the test is complete, click the XML tab.
  7. Scroll down until you see the <AlternativeMailbox> section, and then look for a <Type>Delegate</Type>, as shown in this screen shot.

    Screen shot showing the Test E-mail AutoConfiguration dialog with an automapped mailbox

To remove an automapped mailbox from Outlook, you can use one of the following options:

  1. Remove your Full Access permissions from the mailbox.  This is a good option if you no longer require access to the shared mailbox.

    Manage Full Access Permissions
  2. Remove AutoMapping for the shared mailbox.  This is a good option if you must have access to the shared mailbox, but do not want it AutoMapped in Outlook automatically.

    Disable Outlook Auto-Mapping with Full Access Mailboxes

    2646504 How to remove automapping for a shared mailbox in Office 365

Remove shared Calendar, Contacts, Tasks or Notes folders:

  1. Open Outlook.
  2. Click the Calendar, Contacts, Tasks or Notes folder in the Navigation pane where you have a shared folder open.
  3. Look under “Shared <Folder name>” for any shared folders, as shown in the following screen shots.

    Screen shot showing shared folders of different types

  4. Right-click the shared folder, and then click Delete Folder or Delete Calendar, depending on the folder type.  The following screen shot shows a shared Calendar being removed.

    Screen shot showing how to close a shared calendar folder

    Note Clicking Delete Calendar or Delete Folder on a Shared Calendar or Shared Folder does not delete the folder from the mailbox where it resides.  This only removes it from your Outlook view.

Follow steps 2 through 4 for any remaining shared folders that you want to remove from Outlook.

Close a Shared Inbox Folder:

When you open a shared Inbox folder, it will appear in Outlook only until you click a different folder.  It does not remain in the Folder list.  To remove a shared Inbox folder, click a different folder in your Mailbox and it will close.

Note This is a "FAST PUBLISH" article created directly from within the Microsoft support organization. The information contained herein is provided as-is in response to emerging issues. As a result of the speed in making it available, the materials may include typographical errors and may be revised at any time without notice. See Terms of Use for other considerations.

Article ID: 3136059 - Last Review: 01/14/2016 18:45:00 - Revision: 1.0

Outlook 2016, Microsoft Outlook 2013, Microsoft Outlook 2010

  • KB3136059