DHL claims that it will ensure that the service, which offers mail collection from any organisation within the UK with optional sorting and next day or two-day delivery by DHL, is at least 99% reliable.
The service is being offered within designated postcodes in London and the North West area, which includes Manchester, Liverpool, Stockport and Warrington.
Customers will also be offered larger volume direct mail and publication distribution services, for either next day, two- to three-day or three- to five-day delivery.
Smartmail Citispeed will eventually be expanded to provide delivery to all areas of the UK.
John Ivers, UK managing director of DHL Global Mail, said: "The fundamental factor missing in today's mail services is reliability. By building own network we have 100% control over this. This is why we have embarked on the largest roll-out of a national domestic business-to-business mail service since deregulation was announced."
DHL Global Mail has been created after the integration and re-branding of Speedmail International, which DHL's parent Deutsche Post acquired in January 2004. Deutsche Post was granted a licence by Postcomm in March 2004.
Tim Norman, development director at Mail Marketing International, said: "We've been using the Citispeed service for some time and have found it has made an enormous difference to the reliability, cost and management of mailings."
Gregor McGregor, chief executive of postal services watchdog Postwatch, said it was a good day for postal customers and a landmark date in the development of a competitive postal market.
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