us Personal safety & immediate danger stranger checking door numbers • person looking for apartment number • someone reading mailboxes • suspicious person in hallway • unknown person in apartment building • someone casing apartments • someone loitering by doors • person trying doors in building • someone looking for specific unit • tailgating through secure door • unwanted visitor in lobby • building security concern • mailbox tampering worry • mail theft in apartment building • unsure if delivery or scam • someone asking which unit you are • apartment corridor safety

What to do if…
you see someone checking door numbers or mailboxes in your building while looking for a specific unit

Short answer

Don’t approach them in the hallway. Move behind a locked door (or to a staffed/public area) and notify building management/security; if you think a crime is in progress or someone is at risk, call 911.

Do not do these things

Don’t confront them, block their path, or follow them down the hall.
Don’t open your door to talk, even if they seem “confused” or “in a hurry”.
Don’t hold a secure door for them or let them tailgate into the building.
Don’t tell them your unit number, access codes, or who lives in which unit.
Don’t try to “verify” who they are by walking up to them if you feel uneasy.

What to do now

Get to a safer position. Step back into your unit and lock up, or go to a staffed/public spot (lobby/front desk/leasing office/security desk) without drawing attention.
Secure the entry behind you. If you were entering/exiting, ensure the main/secure door closes and latches. Don’t allow tailgating.
Notify building management/security immediately. Call the front desk, property manager, leasing office, or security and report:
- exact location (floor, hallway, mail area),
- what you saw (checking door numbers/mailboxes, searching for a specific unit),
- description (clothing, approximate age, any bags/tools),
- whether they tried handles, pressured residents for access, or refused to leave.
Call 911 if there’s immediate risk. Call 911 if you believe a crime is happening or about to happen (e.g., trying door handles, forcing mailboxes/doors, threats, stalking, weapons, someone in immediate danger). Give your exact address and the best entrance for responders.
If it’s suspicious but not urgent, use the non-emergency route for your area. Many departments publish a non-emergency number and/or online reporting. Some cities also offer 311; if yours does, it may route you to the right non-emergency option. If you’re unsure, use the police department’s official website to find the non-emergency contact.
If they knock, keep the barrier. Don’t open the door. If you respond, say through the door: “I can’t help. Please contact the resident you’re looking for or the building office.” Then stop engaging.
If you suspect mailbox tampering or mail theft, report it. If you saw someone trying mailboxes, taking mail, or forcing the mail area:
- Call 911 for an active crime in progress.
- Otherwise, report to the U.S. Postal Inspection Service (USPIS) for mail-related crimes.
Document from safety (optional). Write down time, location, and description. Only capture a photo/video if you can do it safely from inside or a public, safer area—without approaching or escalating.
Ask management to reduce risk for everyone. Request a building-wide reminder not to grant access to unknown people, and to report tailgating or mailbox tampering promptly.

What can wait

You don’t need to determine whether they were a legitimate visitor, delivery person, or “casing” right now.
You don’t need to confront them, gather proof, or coordinate residents to “check the halls”.
You don’t need to make purchases or change locks unless there’s evidence of attempted entry or an access breach.

Important reassurance

It’s reasonable to treat this as a safety situation without needing certainty about their intent. Creating distance, keeping doors secure, and involving the right people quickly is a cautious response.

Scope note

These are first steps to stabilise the moment and reduce risk. If the issue repeats, follow-up steps with management and local police can come later.

Important note

This guide is general information, not legal advice. If you feel unsafe or believe a crime is in progress, prioritise a safer location and contact emergency services.

Additional Resources

Support us

What to do if…you see someone checking door numbers or mailboxes in your building while looking for a specific unit