WASHINGTON: When extra terrestrials want to tell their fellow beings, back on their mother planets, what earthlings are like, chances are that they will be visiting the nearest post office rather than rushing to the neighbourhood phone booth, as a new report has indicated that the old fashioned habit of letter writing might be a better way of sending interplanetary messages, than the current fad of e-mails.

According to Nature, engineers at the Rutgers University in New Jersey have found that penning things down is a much more effective way of sending messages, because a physical object would last longer than a beam of radio waves.

The researchers are now asking scientists to keep a sharp lookout for any hefty parcels, because this discovery specially holds true for long messages.

The study suggests that whereas short messages can be sent through radio waves, aliens are likely to send very long ones, and this is best achieved through the written word, because radio waves cannot take too much load.

Researchers aver that extra terrestrials are likely to send a message of atleast 40 million terabits, which is equivalent to all the world's telephone calls in a year.

The other reason why mails are better is because radio waves are likely to start losing connectivity and become undetectable over long distances, whereas a mail has the advantage of staying in the same form.

"Communication by the transmission of matter once seemed ridiculous compared to using radiation, but it's not, and we should be looking for both," the report quoted Christopher Rose, the author of the study, as saying.

"Energy is kind of a currency: if something costs less, it's more likely to get done," he added.