I keep getting outlook reminders for a calendar I already deleted

Question

I keep getting Outlook reminders for a calendar I already deleted. I ran the CMD below but it didnt help.

outlook.exe /cleanreminders

I am also taking the following steps next:

1.
Right-click the affected calendar and select Properties > Clear Offline Items > OK. All items on the calendar will be removed.

1. Select Send / Receive > Update Folder in the ribbon to force the items' download.

What should I do next?

Answer 1

Hi @George Ortega,

Good day and thank you for clearly presenting your concern.

Outlook reminders are stored in a hidden Reminders folder in the mailbox. When a calendar or recurring meeting is deleted, the reminder entries can sometimes remain orphaned. Outlook then continues to surface the reminder even though the calendar item no longer exists

You can try follow the steps below and deep clean your deleted items:

The problem occurs with deleted and canceled meetings in the Outlook desktop client when you have mailboxes hosted on the Exchange Server or Microsoft 365.

When you delete events from your Outlook calendar, they are moved to the Deleted Items folder, and continue to send popup notifications (reminders). First, try deleting events from this folder.

Switch Outlook to Folder View and select the Deleted Items folder. If you have deleted a meeting or other calendar event, find it, right-click it, and delete it permanently.

Deleted Outlook calendars are a special type of container that will also appear in the “Deleted Items” folder. In this calendar, you will also find events with reminders. Delete all the events in the calendar one by one, and then delete the calendar itself.

If there are any other calendars connected in the settings of your Outlook mail profile, delete them as well (Control Panel -> Mail -> Email accounts -> Internet Calendars tab).

After that, it would help if you ran Outlook with the /cleanreminders parameter to clean up old reminders in the mailbox calendar:

1. Close the running Outlook app;
2. Click Win + R and run the command: outlook.exe /cleanreminders

Some of your calendar events and reminders cannot be deleted from Outlook. An error may occur when removing a meeting request:

This meeting cannot be removed because you are the meeting organizer.

Even if the original calendar event has been deleted, reminders for such an event may still appear. This indicates that the event reminder is corrupt.

In this case, try deleting the calendar item using the MFCMapi (Microsoft Exchange Server MAPI Editor).

1. Download the MFCMapi tool (https://github.com/microsoft/mfcmapi/releases/);
2. Expand Root-Mailbox > Finder > Reminders;
3. Find a recurring meeting by sorting the list by the Subject column;
4. Click on the meeting and select Delete Message;
5. In some cases, also check the Deleted Items folder in MFCMapi. Find a recurring calendar reminder manually or with a search. Delete with the DELETE_HARD_DELETE option.
6. Start Outlook with the option to clean up reminders: outlook.exe /cleanreminders

More information about this can be found at: Calendar reminders in Outlook can't be dismissed or keep reappearing - Exchange | Microsoft Learn

I hope this provides enough clarity and helps you stay inform with your current situation.

Thank you for your patience and your understanding. If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.    

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Answer 2

Because outlook.exe /cleanreminders and clearing offline items did not stop the reminders, the next step is to remove the corrupted reminder entries directly from the Reminders folder by using MFCMAPI, then recreate the reminders store.

Follow these steps carefully (they modify mailbox data):

1. Download and open MFCMAPI
   1. Download MFCMAPI from GitHub (Latest release).
   2. In Outlook, select Send/Receive > Work Offline, then close Outlook.
   3. Run MFCMapi.exe.
2. Log on to the mailbox
   1. In MFCMAPI, select Session > Logon and Display Store Table.
   2. Select the mail profile that contains the problematic calendar and select OK.
   3. Right‑click the mailbox store and select Open Store (or double‑click it, depending on version).
3. Open the Reminders view and delete the bad reminder(s)
   1. In the left tree, expand Root-Mailbox (or Root Container, depending on version).
   2. Expand Finder.
   3. Double‑click Reminders.
   4. In the item list, locate the appointment(s) that correspond to the deleted calendar/reminder (sort by Subject or To to find them).
   5. Right‑click the offending appointment/reminder and select Delete Message.
   6. In Delete Item, choose a permanent deletion option and select OK.
4. Rebuild the reminders cache
   1. Close MFCMAPI.
   2. Start Outlook with the reminders cleanup switch again: press Start, type:

            outlook.exe /cleanreminders
      

      and press Enter.
   3. Let Outlook fully start and verify that the phantom reminders no longer appear.

If reminders still persist after this, repeat the MFCMAPI steps to confirm no stale entries remain in the Reminders folder, then optionally run Outlook.exe /ResetFolders to recreate default folders and views.

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References:

• Calendar reminders in Outlook can't be dismissed or keep reappearing
• You can't remove a calendar item or an email message in Outlook in Microsoft 365
• Outlook shows conflict errors when updating or cancelling meetings