Wells Fargo & Co. (WFC) announced that all deposit-taking ATMs in its network of more than 12,000 machines in the U.S. are now entirely envelope-free.

"Some key benefits are they do the math, save paper, simplify the process and extend the banking day," Alicia Moore, head of Wells Fargo ATM Banking said in a statement.

Customers no longer need to write on an envelope or key-in a deposit amount. Once cash or checks are inserted, the machine converts the paper checks into digital images, which appear on the ATM screen and on the receipt. It also sorts and counts the bills and verifies the amount.

Cash deposits are available for use immediately and check deposits made on weekdays by 9 p.m. are considered received on the same day, the company said.

The reasons behind this push is threefold, David Aldertazzi told the International Business Times. Aldertazzi is a senior analyst at Aite Group, an independent research and advisory firm.

The main driver is to mitigate ATM deposit fraud. With the old envelope deposit method, "there are a higher number of occurrences in terms of fraud, rather than when they are envelope-free," Aldertazzi said.

Also, envelope-free ATMs can reduce the cost of deposits and enhance the overall customer experience.

According to the bank, its ATMs equipped with the new technology have already processed over 331 million checks and helped eliminate the use of more than 321 million paper envelopes, which equates to the conservation of 4,707 tons of paper, or 32,617 trees.

Citibank (C) stated in its recent edition of client manual for consumer accounts that the bank will be installing new envelope-free ATMs at Citibank branches and other Citi locations "throughout 2011."

Citibank operates more than 3,200 ATMs in over 1,000 bank branches, according to the bank's website.