The executive director of the Hillel Foundation at Penn was the latest victim of a recent rash of terroristic threats across the country, according to the University Police.

All of the incidents reported so far have been similar to the one that threatened Rabbi Howard Alpert at Hillel April 25. In each case, someone received either a letter or package filled with a substance that the sender claimed was anthrax or an anonymous phone call from a person who claimed to have placed the potent toxin inside a building.

So far, the substances involved in each incident have proved to be non-toxic. But the incidents underscore the continued need to be aware of potential dangers in the mail. You cannot be sure beforehand that a chemical or bomb threat is not the real thing.

The UPPD advises that suspicious letters or packages usually have one or more of the following characteristics:

Excessive postage

Incorrect titles

Titles without names

Oily stains or discoloration

Rigid envelopes

Restrictive makings such as “Confidential” or “Personal”

Excessive securing material such as masking tape or string

Lopsided or uneven envelopes

No return address

Poorly written or typed envelopes

If you receive an envelope or package with more than one of these characteristics, you should exercise caution. Do not panic, but do not touch, move or open the envelope or package. Call the UPPD at 511 (on-campus extensions) or 215-573-3333 (off-campus phones) to have an expert examine the package if you have reason to believe it is suspicious.