Moves to put all GPs on to the NHS's national communications network are being delayed amid a flood of complaints about the unreliability of its electronic mail service.

Users claim messages passing through the 'gateway' from NHSnet to the Internet have been lost or corrupted, while e-mail sent between NHS users often bounces back. When it is delivered, delays sometimes exceed 24 hours and file attachments are lost.

Systems consultant Barry James recently conducted a survey at Leicester Royal Infirmary, which showed 60 per cent of its users have seen e-mail go astray, despite being correctly addressed.

There is 'substantial frustration that may be undermining the usefulness of NHSnet', said Mr James, adding that the main problem was that NHSnet users were sending a lot of e-mail to the Internet, as well as within the NHS.

They are also adopting Internet-style e-mail addresses instead of the lengthy addresses allocated by the NHSnet messaging service.

The upshot has been regular crashing of the messaging service, with messages bounced back to the sender or completely destroyed.

Without rapid action there could be repercussions for the£40m GPnet project, under which all GPs are supposed to be connected to NHSnet by the end of this year.

Alan Hassey, a Wakefield GP who serves on a joint computing group set up by the clinical professions, has refused to use NHSnet until it is fixed. 'It is currently inadequate for primary care and it does not provide what GPs could get from any Internet service provider,' he said.

Syntegra, the company that built the NHSnet messaging service, has now installed an upgrade that it claims will stop e-mail being lost in transit between NHSnet and the outside world.

A 'relay' service will be installed to help cure the bouncing message problem 'within a few weeks', said Syntegra health team marketing manager Richard Harris.

Ewan Davis, managing director of GP system supplier AAH Meditel, said: 'It's been agreed for nearly a year that this problem needs to be sorted out, but we have not seen much real progress.

'Worse, the mail service is down far more than one would get with an Internet provider - typically 24 to 48 hours at a stretch.'

Further delay may accelerate the trend for both GPs and the new primary care groups to bypass NHSnet and go straight to Internet service providers, he said.

Bob Grindrod, director of the GPnet project at the NHS Executive, agreed there was dissatisfaction with the e-mail service. But he added: 'I'm confident that the service will be of the quality we require for GPnet when the relay service is introduced.'

The business case for GPnet has still not yet been approved by the Treasury. Mr Grindrod is negotiating with ministers over the specification of the new equipment to be ordered for GPs and how the funds will be managed.

Leicester Royal Infirmary is hosting a national survey on NHSnet problems.