Industry sources said Saturday that online greeting cards are gaining popularity with the rising number of Internet users.

The sources said internet card delivery companies were extremely busy during the last Christmas season, recording three to six times their daily average volume.

On the other hand, paper Christmas and New Year's cards delivered through the conventional mail fell 4 percent from a year earlier to 42.75 million.

The Internet card leader Send2U, which delivers 120,000 to 150,000 cards a day, saw its volume surge to 340,000 on Dec. 24.

According to Internet Metrix Inc., which specializes in Internet interface statistics, hits on Internet card sites surged during the last holiday season, causing delays when the tremendous demand caused some Web sites to temporarily go down.