Tentative Meeting Invites in Microsoft 365: Behavior, Limitations, and Workarounds

? Overview

In Microsoft 365, meeting invites received by user mailboxes are automatically placed in the calendar as Tentative until the user explicitly accepts or declines the invite. This article explains the behavior, technical limitations, and available workarounds, along with recommendations for enhancing email security.

? Default Behavior

• Tentative Entries: By design, when a meeting request is sent to a user, it is immediately displayed in the calendar as Tentative.

• Consistency: This behavior is consistent across Outlook Desktop, Outlook Web App (OWA), Microsoft Teams, and mobile clients.

• Purpose: Helps users visualize potential scheduling conflicts before making a decision.

⚙️ Technical Details

Resource Mailboxes (Rooms/Equipment)

• Use the following PowerShell command to control auto-processing for resource mailboxes:

  Set-CalendarProcessing -Identity "room1@domain.com"

• Official Documentation: Set-CalendarProcessing (Microsoft Learn)

User Mailboxes

• Settings can be modified with:

  Set-MailboxCalendarConfiguration -Identity "user@domain.com"

• Limitation: There is no parameter to disable tentative entries or restrict visibility to only accepted meetings.

• Official Documentation: Set-MailboxCalendarConfiguration (Microsoft Learn)

✅ Workarounds

Outlook Desktop (Classic)

• Navigate to Calendar > View > View Settings > Filter > Advanced

• Add filter criteria:

  • Field: Meeting Status

  • Condition: Equals

  • Value: Accepted

• This view will now display only accepted meetings.

Outlook Web App (OWA)

• Open Calendar → Select Filter icon

• Under Appointments → Meetings, choose Accepted.

Microsoft Teams Calendar

• Open Teams → Calendar → Select Filter

• Under “I’m an attendee” → choose Accepted.

Mobile Clients (Outlook Mobile, Native iOS/Android Calendar)

• No filter option available. Tentative meetings will always display.

• For further clarification, users can contact Outlook Mobile In-App Support.

⚠️ Limitations

• Tentative placeholders cannot be suppressed for user mailboxes.

• Even with AutomateProcessing = None and TentativePendingApproval = False, the system still creates tentative entries.

• Filters only affect viewing, not the creation of tentative entries.

? Email Security Recommendations

To minimize spam or malicious meeting invites:

1. Enable Anti-Phishing Policies – Protects users from spoofing and impersonation.

2. Configure Anti-Spam & Anti-Malware Policies – Reduces unwanted invites.

3. Enable Microsoft Defender for Office 365 (Safe Links & Safe Attachments) – Protects against malicious links and attachments.

4. Implement Data Loss Prevention (DLP) & Sensitivity Labels – Adds governance for sensitive data.

5. Enable Multi-Factor Authentication (MFA) – Prevents mailbox compromise.

6. Conduct User Training – Educates users on handling suspicious invites safely.

? Next Steps

• Apply filters in Outlook Desktop and OWA to focus only on accepted meetings.

• Be aware of limitations on Outlook Mobile and Teams.

• Review and strengthen Microsoft 365 email security to reduce calendar spam.

• Contact IT or Microsoft Support for advanced guidance or automation options.

? References

• Set-CalendarProcessing (ExchangePowerShell)

• Set-MailboxCalendarConfiguration (ExchangePowerShell)