Outlook MailTip ‘Recipient Is Out of Office’ Threshold: How to Configure

When you compose an email in Outlook, a MailTip may appear warning you that the recipient is out of office. By default, Outlook displays this tip for every recipient who has an automatic reply set. For large distribution groups or frequent bulk mailings, this generates excessive on-screen warnings that slow down message composition. This article explains how the out-of-office MailTip threshold works and provides the exact steps to configure the number of recipients that trigger the tip. You will learn to adjust the setting in Exchange Online PowerShell and in the Exchange Admin Center.

How the Out-of-Office MailTip Threshold Works

Outlook MailTips are server-side policies that display contextual warnings in the message composition window. The out-of-office MailTip appears when at least one recipient on the To, Cc, or Bcc line has an automatic reply configured. For performance and usability reasons, Exchange Online limits the number of recipients it checks for automatic replies. This limit is called the MailTipMailboxCountThreshold and defaults to 25. When the recipient count exceeds this value, Outlook stops checking for out-of-office status and shows a generic warning instead, such as “The recipient is out of office or has set automatic replies.”

This threshold is separate from the large audience threshold, which warns when you send to a large distribution group. The out-of-office threshold applies specifically to the count of unique recipients whose automatic reply status is evaluated. Administrators can raise or lower this value to balance between useful warnings and performance overhead. Raising the threshold increases the load on the Exchange server because it must query the automatic reply status for more mailboxes. Lowering the threshold reduces server load but may cause the warning to appear for smaller groups incorrectly.

Prerequisites for Configuration

To change the out-of-office MailTip threshold, you need the following:

• Exchange Online PowerShell module installed (ExchangeOnlineManagement)
• Global Administrator or Exchange Administrator role in Microsoft 365
• Access to the Exchange Admin Center (EAC) for GUI-based changes

Steps to Configure the Out-of-Office MailTip Threshold via PowerShell

The most direct method to set the threshold is through Exchange Online PowerShell. The following steps assume you have the ExchangeOnlineManagement module installed and are connected to Exchange Online.

1. Connect to Exchange Online PowerShell
   Open Windows PowerShell as an administrator and run Connect-ExchangeOnline. Sign in with your administrator credentials when prompted.
2. Check the current threshold
   Run Get-Mailbox -Identity "user@domain.com" | fl MailTipMailboxCountThreshold. Replace the identity with any mailbox in your organization. The default value is 25.
3. Change the threshold for a specific mailbox
   Run Set-Mailbox -Identity "user@domain.com" -MailTipMailboxCountThreshold 50. This sets the threshold to 50 for that mailbox only. The value must be an integer between 0 and 99999. A value of 0 disables the out-of-office MailTip.
4. Apply the threshold to all mailboxes
   To set the same value for every mailbox in the organization, run Get-Mailbox -ResultSize Unlimited | Set-Mailbox -MailTipMailboxCountThreshold 50. This command may take several minutes depending on the number of mailboxes.
5. Verify the change
   Run Get-Mailbox -Identity "user@domain.com" | fl MailTipMailboxCountThreshold to confirm the new value is applied.

Steps to Configure the Threshold via Exchange Admin Center

The Exchange Admin Center does not expose the MailTipMailboxCountThreshold property directly. However, you can enable or disable MailTips and adjust the related large audience threshold from the EAC. The out-of-office threshold itself must be set through PowerShell. Use the EAC for organization-wide MailTip settings and PowerShell for the per-mailbox threshold.

1. Open the Exchange Admin Center
   Go to https://admin.exchange.microsoft.com and sign in as an Exchange administrator.
2. Navigate to Mail Flow
   In the left navigation panel, select Mail flow, then click MailTips.
3. Adjust the large audience threshold
   Under MailTips settings, find Large audience size. This value sets the threshold for the “Your message has been sent to a large number of recipients” warning. It does not directly control the out-of-office threshold but interacts with it. Set this to your preferred number, then click Save.
4. Enable or disable MailTips
   Toggle the Enable MailTips switch on or off as needed. Disabling MailTips turns off all MailTips, including the out-of-office warning.

If the MailTip Still Behaves Incorrectly After Configuration

The out-of-office MailTip appears for every recipient even after raising the threshold

This usually happens when the threshold was set on a mailbox that is not the sender’s mailbox. The MailTipMailboxCountThreshold is a per-mailbox setting that controls how many recipients are checked for that specific mailbox. If you changed the threshold on a test mailbox but the sender uses a different mailbox, the old threshold still applies. Verify the identity of the sender’s mailbox and apply the change to that mailbox directly.

The out-of-office MailTip does not appear at all

If the threshold is set to 0, the MailTip is disabled. Run Get-Mailbox -Identity "sender@domain.com" | fl MailTipMailboxCountThreshold to confirm the value is not 0. Also check that MailTips are enabled in the Exchange Admin Center under Mail Flow > MailTips. If MailTips are enabled globally and the threshold is above 0, verify that the recipient actually has an automatic reply configured. The MailTip only appears when the recipient’s mailbox has an out-of-office rule active.

The threshold change does not take effect for shared mailboxes

Shared mailboxes have their own MailTip threshold setting. Run Get-Mailbox -RecipientTypeDetails SharedMailbox | Set-Mailbox -MailTipMailboxCountThreshold 50 to apply the threshold to all shared mailboxes. The same command works for resource mailboxes by changing the RecipientTypeDetails filter to RoomMailbox or EquipmentMailbox.

Item	Per-Mailbox Threshold (PowerShell)	Organization-Wide Setting (EAC)
Configuration method	Set-Mailbox -MailTipMailboxCountThreshold	MailTips settings in EAC > Mail Flow
Scope	Single mailbox or all mailboxes via Get-Mailbox pipeline	Entire organization
What it controls	Number of recipients checked for out-of-office status	Enable/disable MailTips, large audience threshold
Default value	25	25 (large audience threshold)
Requires admin role	Exchange Administrator or Global Administrator	Exchange Administrator or Global Administrator

You can now adjust the out-of-office MailTip threshold to match your organization’s sending patterns. Start by checking the current value on a test mailbox, then apply the change to all mailboxes if needed. For fine control, set different thresholds for different user groups using PowerShell filters. Remember that raising the threshold increases server load, so test the new value in a pilot group before rolling it out organization-wide.