Hard-hit by an avalanche of incoming spam messages, ISP Ihug has decided to introduce further checks on servers wanting to send email to its customers. From now on, email servers must have matching reverse and forward pointing records in the Domain Name System (DNS) for messages to be accepted by Ihug’s SMTP (Simple Mail Transfer Protocol) servers.
But this move to combat spam was criticised by at least one New Zealand network operator because Ihug’s servers simply reject messages with any SMTP error codes to let the sending hosts know what is going on.
In doing so, the sending email servers are likely to continue trying to connect to Ihug’s servers, which may increase the load on the latter. An Ihug network engineer agreed with the operator in question, saying dropping connections to mail servers without explanation is unhelpful to say the least.
And there are further email headaches for Ihug: its outgoing mail servers are listed on the Spam and Open Relay Blocking (SORBS) blacklist. SORBS is widely used by organisations such as Telecom and Microsoft to either reject mail outright, or to score suspected spam. Ihug customers are reporting that mail to Telecom is blocked at the moment.
Relihan Myburgh, engineering manager at Ihug, says the provider has applied for the blocked range to be removed from SORBS but hasn’t had a response yet. Nobody answers the phone or email at SORBS, Myburgh says. He points out that Xtra was also listed two years ago for three weeks and could do nothing about it. This was because some Xtra customers sent bulk spam, according to Myburgh.
Saying fully automated systems like SORBS are a pain because they’re so easy to be accidentally be listed on it, Myburgh favours Ironport’s Senderbase scoring system as far superior. It uses half human input combined with half computerised algorithms and can be contacted for de-listing after checks have been made.
With the likes of SORBS, Myburgh says, you have to plead with a power-hungry geek who likes to play God with your email system before they will agree to de-list you.
Matthew Sullivan from SORBS says that he doesn’t know for sure why Ihug’s netblock is listed.
When asked by Computerworld, he said someone logged a ticket on the listing on November 13 and the reverse DNS entries have been updated, but provided no further comment on whether or not Ihug’s mail servers would be de-listed.