Have you ever written a nasty letter to someone only to wish you hadn't, then wished you could somehow get the letter back.

Well, you can. But you have to act fast, says John Faircloth, supervisor of claims and inquiry for the Salt Lake Post Office.Faircloth says it is quite common for people to want to recall mail they have sent - for one reason or another. Postal Service Form 1509 is designed to help these people, but there is so much mail in the postal system, and modern equipment and postal methods have speeded up delivery to such a degree, that it is difficult if not impossible sometimes to recall a single letter or package.

"If you have mailed something by mistake - if you have mailed a letter without a stamp or failed to include a check or some other material in a letter - or written a letter in anger, the best thing to do is to inquire at the post office where you mailed the item. Ordinarily, if you have mailed it at a small post office, you can usually go to a postal window and explain your problem and the clerk will help you.

"If you have just mailed the item, it should be easy to find it. But, if you have mailed some thing at a post box on the street or in a building - but not at a post office - you will have more difficulty. Go to the post office that would collect your letter or package and explain your problem as soon as possible.

"If the item you mailed is still in the box, you have a good chance of recalling it. If it has been picked up and has been taken to the post office to be processed, you have a more difficult problem."

Faircloth says the U.S Postal Service handled 153 billion pieces of mail last year, and millions of pieces of mail enter and leave the Salt Lake Post Office at 1760 W. 21st South every day.

"It is understandable if we can't find a letter once it is in the system, although we try. I won't say it is impossible - but it is nearly impossible."

Companies that mail thousands of pieces of mail by mistake have a better chance of recalling their mail because it can be traced. "That much mail stands out. Companies do have problems with their mail, and it is not unusual for companies to recall large shipments of mail, and we have a good record for helping them.

"I get calls all the time from people who have mailed things by mistake or who want to recall an item. They sometimes offer to come down to the post office and look for it themselves. We tell them no. Only postal employees are allowed on the floor in the first place, but with all the mail being processed, looking for one letter is just not practical.

"It is like looking for a grain of sand on a beach."