Telecom says increasing volumes of spam and increasingly clever ways of masking spam is keeping them busy.

Some Christchurch consumers have complained of long delays in receiving e-mails over the past couple of days.

Telecom spokesman Nick Brown says the problem is not widespread but they have had about a hundred extra calls this week complaining of a slow e-mail service.

He says November has been a particularly bad month and they have been filtering out about 20 million pieces of spam a day.

Mr Brown says some delays may be linked with this filtering process.