A standard piece of advice for staying safe online is to avoid opening attachments from people you don’t know or attachments that seem suspicious. It’s good advice, since PDFs and office documents can contain JavaScript and macros that present a security risk, or they could be maliciously crafted to take advantage of vulnerabilities in common apps to execute code on your computer.
But in the real world, unless the document is attached to a message that is obviously spam, it’s difficult to know whether you should be worried. If you could just look at the document, you might be able to tell, but how can you do that without opening it? Read More from “View Suspicious Documents Safely with Dangerzone”
button in the upper-right corner, tap Manage Filtering, and turn on Screen Unknown Senders and Filter Spam. Once those are enabled, the Filter menu gains two new options: Unknown Senders and Spam. If a text from an unknown person comes in, the main app icon will get a red badge, but you won’t see the new message in the usual list. Instead, use the Filter menu—which also gets a blue badge—to switch to Unknown Senders or Spam and look in those lists. The Phone app works similarly—enable call filtering in Settings > Apps > Phone under Call Filtering, and unknown callers will appear in separate lists accessible via the Filter button in the Phone app’s Recents or Calls views. To move a conversation out of Unknown Senders, tap Mark as Known. 
