Most receptionists receive, open, date stamp and sort all of the incoming company mail. Someone who previously trained them gave them five minutes of advice as to what to toss and what to actually physically distribute to employees. Most of the time mail that was addressed to a currently employed individual is generally forwarded, but the pieces of mail which are addressed to ex-employees are many times tossed in the trash. This may be a mistake given that companies send discounts to ex-customers, statements that hold savings if used for purchases or just great leads on potential cheaper vendors. Your staff will not know any of this unless the mail is distributed and reviewed by another level staff member.
Tell the receptionist to go through the mail and keep those items she would normally toss, and forward them to someone trained. Take the time to review this pile of mail that is being thrown away. There are always catalogs, advertisements, flyers, brochures on seminars and training sessions for various companies. Some of the items that are tossed out should be, but some deserve a closer scrutiny.