Launching this week, the service will allow businesses and consumers to send Christmas cards through the Royal Mail site (www.royalmail.com).
It will offer a range of cards, with more than 3,000 designs, and will also allow firms and consumers to design their own cards. Personalised messages, logos and signatures can be included, and Royal Mail will manage mailing lists and postage.
Royal Mail is partnering with web greetings card firms Moonpig (www.moonpig.com) and Sharpcards (www.sharpcards.co.uk) to provide the service.
Customised cards designed by Moonpig can be ordered up until 18 December, with prices from £2.99. 'Ready to go' cards produced by Sharpcards will cost from about £2.
Promotional emails will be sent to more than 60,000 users from Royal Mail's database, with banners running on sites such as Barclaycard's ShopSmart and Debenhams.
According to Royal Mail, it is the first time it has offered the service on this scale. "We tried it for Mother's Day, but this is the first time we've brought it all together as an integrated offer," said David Worsfold, head of market development at Royal Mail. "Greetings cards are big business," he added. "There is a trend towards e-cards, but they don't have the same impact."