Large numbers of Apple users are reporting that they've received spam calendar invitations and/or photo-sharing invitations, many of them to dubious Black Friday sales events. And those who decline the invitations will likely find themselves getting much more such spam in the future, experts say.

Not much is known so far about the source of the spam invites, many of which are in Chinese and offer deals on Ray-Ban sunglasses or Ugg boots. A spokesperson for Ugg's parent company told CNBC that it does not do promotions by calendar invite. Ray-Ban's parent company and Apple have not yet commented.

Although most people have become accustomed to receiving spam in their email and sometimes via text message, the practice of sending out spam calendar invites is relatively new and highly unsettling to many who've received them.

If it happens to you (or someone you know), here's what to do about it.

1. Don't worry that your security has been compromised.

Some Apple users tweeted their worries that having spam invites appear in their calendars meant their passwords had been compromised. That's not the case. Most calendar software is set so that calendar invitations automatically appear as events that can be accepted or declined. That's a setting that can be changed.

2. Don't click "decline."

If you do, you'll be letting the spammers know that yours is an active account, and you'll most likely get even more calendar spam.

3. Move the event to a different calendar.

If you don't decline the invite, are you stuck with it on your calendar forever? Not if you don't want to be. 9to5Mac offers a clever workaround: Create a second calendar for unwanted appointments, move the invites there, and then delete that second calendar. (Here's a more detailed description of how to do this.) Unfortunately, you will have to do this on a computer; it's very awkward to do on an iPhone or iPad.

4. Change your settings.

An Apple user who comments on the 9to5Mac story also suggests a simple way to stop spammy invites from appearing in your calendar: Set your preferences to email notifications rather than in-app notifications. (Read the first comment for his full explanation of how to do this.)

It will mean giving up the convenience of having event invites appear in your calendar but if you're getting spam invites on a regular basis, you're probably happy to make that trade. Unfortunately, there's no similar option for photo sharing, so if you're getting spam photo-share invitations, the only way to make them stop is to disable photo sharing altogether.

It's just one more useful thing that spammers will have ruined--unless Apple finds a way to fix it.

Published on: Nov 26, 2016