Open relay spam is dying out as a problem, according to a survey published today that is likely to raise eyebrows in the spam-fighting community.

Only one per cent of corporate UK mail servers tested by security testing firm NTA Monitor last year were poorly configured in a vulnerable way that allowed spam to be distributed by 'open relay'. In 1997, 91 per cent of servers tested by NTA Monitor were similarly vulnerable.

Even so NTA's Monitor's findings fly in the face of conventional industry wisdom on the topic and are likely to prove controversial.

Open to abuse

Spammers traditionally used 'open relays' to distribute their spam. Open relays allowed spammers to off load the job of sending thousands of emails to a powerful server with high bandwidth. The practice slows down the processing of legitimate email and clogs up bandwidth, to say nothing of the potential damage to reputation that comes from even innocently sending out spam.

Years ago spammers were spoilt for choice for open relays, but now the window for exploitation of corporate mail servers has reduced dramatically, according to NTA Monitor.

So why has the tactic declined?

"The dramatic fall is due to manufacturers making it easier to turn off 'open relaying' functionality in their mail server products and disabling it in their default settings, in addition to understanding of the problem and its remedies from security staff," NTA Monitor states. ®