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How do I stop spam calendar invitations?

If suspicious or unwanted events are appearing on your calendar, they are almost certainly calendar spam — unsolicited invitations sent by spammers or phishers. These invitations are delivered and added by your calendar server, not by BusyCal.

Why BusyCal cannot filter these​

BusyCal syncs events from your calendar account exactly as the server provides them. It has no way to distinguish a legitimate meeting invitation from a spam one — that determination can only be made by the calendar service that receives and stores the event. This is the same for any third-party calendar app.

The filtering and reporting must be done on the server side, through the web interface of your calendar provider. Do not attempt to accept, decline, or delete spam invitations from within BusyCal — instead, use the instructions below to report and remove them directly from your provider's web portal, where dedicated spam-reporting tools are available.

Don't interact with spam invitations

Never click links, call phone numbers, or tap Accept or Decline on a suspicious invitation — whether in BusyCal, Apple Calendar, or any other app. Responding in any way — even declining — confirms to the spammer that your email address is active and may lead to more spam. Always handle spam through your provider's web interface as described below.

Google Calendar​

Google Calendar can automatically add invitations to your calendar the moment they arrive, even from unknown senders. This is the most common source of calendar spam.

Prevent spam invitations​

  1. Open calendar.google.com in a web browser.
  2. Click the gear icon, then choose Settings.
  3. Under General > Event settings, find "Add invitations to my calendar".
  4. Change it from "From everyone" to one of:
    • When I respond to the invitation in email — events only appear after you explicitly respond via email. This is the most restrictive option.
    • Only if the sender is known — events are added automatically only from people in your contacts or who you've interacted with before.

Report and remove spam​

Spam events should be reported from Google Calendar on the web — not from BusyCal — so that Google can track and block the sender:

  1. Go to calendar.google.com in a web browser.
  2. Click on the spam event to open it.
  3. Click the three-dot menu (More options).
  4. Select Report as spam.

This removes all events from that sender and helps Google improve its spam filtering. After reporting, the event will disappear from BusyCal on the next sync.

note

Only events that were sent through Google Calendar can be reported as spam using Google's reporting tool. Events created by another provider or app cannot be reported this way — simply delete them instead.

Official Google support articles​

iCloud​

iCloud calendar spam typically arrives as an invitation that shows up across all your Apple devices.

Report and remove spam​

Do not decline or delete the event from BusyCal or Apple Calendar — instead, use iCloud on the web where Apple provides a dedicated "Report Junk" button:

  1. Go to icloud.com/calendar and sign in with your Apple Account.
  2. Click on the spam event to open it.
  3. Click Report Junk, then confirm by clicking Delete and Report Junk.

This removes the event from all devices synced with your iCloud account and reports it to Apple. After reporting, the event will disappear from BusyCal on the next sync.

On iPhone or iPad, if you receive a calendar notification from an unknown sender, you can also tap Report Junk directly from the notification or from the event detail screen in the Calendar app.

Check for subscribed spam calendars​

Sometimes spam arrives not as an invitation but as a subscribed calendar that was unknowingly added (often through a deceptive website prompt). To check:

  • On iPhone/iPad: Go to Settings > Apps > Calendar > Accounts (or Settings > Calendar > Accounts on older iOS). Look under Subscribed Calendars for any you don't recognize and delete them.
  • On Mac: Open Calendar > Settings > Accounts and look for unknown subscribed calendars.

Official Apple support articles​

Outlook / Microsoft 365​

Report and remove spam​

Handle spam events from Outlook on the web rather than from BusyCal:

  1. Go to outlook.live.com (personal) or outlook.office.com (work/school) and sign in.
  2. Open the Calendar view.
  3. Right-click the spam event and choose Report as Junk or Report as Phishing.

If you delete a spam event instead of reporting it, choose Do not send a response when prompted — this avoids confirming your email address to the spammer.

note

Older versions of classic Outlook for Windows may not show the Report button for calendar items. If you don't see it, update to the latest version or use Outlook on the web instead.

Block specific senders​

  1. Open Outlook on the web.
  2. Go to Settings (gear icon) > Mail > Junk email.
  3. Under Blocked senders and domains, add the email address or domain that is sending the spam.

Turn off automatic calendar processing (optional)​

By default, Outlook automatically adds invitations to your calendar. You can change this:

  1. Go to Settings > Calendar.
  2. Look for options related to automatic meeting processing and adjust them to require manual acceptance.

Note that disabling automatic processing means legitimate invitations will also need to be manually accepted.

Official Microsoft support articles​

Fastmail​

Fastmail uses CalDAV for calendar sync and does not have a dedicated calendar spam reporting tool. However, because Fastmail processes calendar invitations from incoming email, its email spam filter serves as the first line of defense. Manage these settings from the Fastmail web interface:

Strengthen spam filtering​

  1. Sign in at fastmail.com.
  2. Go to Settings > Filters & Rules > Spam protection.
  3. Under Protection level, choose Aggressive or Custom to increase the spam score threshold.

Block specific senders​

  1. Go to Settings > Filters & Rules > Blocked senders.
  2. Add the email address or domain sending the spam invitations.

If a spam invitation has already been added to your calendar, delete the event from the Fastmail web calendar or from BusyCal — since Fastmail does not have a separate "Report Junk" flow for calendar events, simply deleting it is sufficient.

Official Fastmail support articles​

Other CalDAV Servers​

For self-hosted or other CalDAV servers (Synology, Radicale, Baïkal, etc.), calendar spam is uncommon because these servers typically don't process email-based invitations automatically. If you do receive spam, delete the event directly and check your email server's spam filtering to block the sender.

General Tips​

  • Never click links in a suspicious calendar event — they may lead to phishing sites.
  • Never respond (Accept, Decline, or Maybe) to a spam invite — any response confirms your email is active.
  • Report before deleting when your calendar service offers a "Report Junk" or "Report as Spam" option. This helps the provider improve filtering for everyone.
  • Check for rogue subscribed calendars — some spam arrives through calendar subscriptions that were unknowingly added via deceptive website pop-ups, not through invitations. Look in your calendar account settings for unfamiliar subscribed calendars and remove them.
  • Use a separate email for public-facing sign-ups and forms to reduce the chance of your primary calendar-linked email being targeted.

See Also​

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