BT SDSL Users Suffer E-Mail Problems
Posted: 17th Jan, 2006 By: MarkJ
It's being reported that some SME customers of BT's Business SDSL products are experiencing problems sending e-mail. The issue is a little complex, but has to do with the way BT has set up its service:
Most email servers and junk mail (or spam) filters have the ability to use something called Realtime Black Lists (RBLs). These RBLs are lists of IP addresses which have been flagged or "blacklisted" for various reasons, including known spam offenders and insecure relay servers. Some RBLs also contain lists of Dynamic IP addresses, again a common source of spam.
The SME we spoke with today noticed after only a couple of weeks use that some emails being sent were getting bounced back as undeliverable. Upon further investigation of the problems, it came to light that the IP range assigned by BT to the SDSL products is classed as Dynamic by a couple of RBL providers, due to the Reverse DNS (rDNS) lookup of the IP range. Conducting a reverse lookup on the IP of the BT Business SDSL lines does indeed show they resolve back to "host81-137-*-*.in-addr.btopenworld.com". Because of this rDNS issue, the SME is now finding it more and more difficult to send email out, as more and more companies are employing the use of RBLs on their email gateways.
We asked if the SME had contacted BT Business about these issues. The SME told us they had asked BT to change the rDNS entry for their IP or range, but were told BT were unable to do this. The customer then asked for the IP address of a relay server through which they could send their email via the BT SDSL email relay server. At this point, the customer was informed that only 7 domain names were allowed to relay, per SDSL connection. This meant the customer could have only added a maximum of 14 domains (due to having two SDSL lines) to the BT relay server. The problem there is that the SME in question has 104 domains that are used for email purposes. There is no mention of a seven-domain limit within the terms and conditions of the SDSL contract. The SME then went on to ask if BT could add their email server IPs as "trusted", to the BT relay server, enabling them to send email from any of their domains. Once again, BT said this was not possible.
Typically the SME in question has thus found itself stuck in a contract for a service that is not working as intended.
The I.T.Vibe piece makes for interesting reading, especially at a time when BT is desperate to promote and sell its SDSL products.
Most email servers and junk mail (or spam) filters have the ability to use something called Realtime Black Lists (RBLs). These RBLs are lists of IP addresses which have been flagged or "blacklisted" for various reasons, including known spam offenders and insecure relay servers. Some RBLs also contain lists of Dynamic IP addresses, again a common source of spam.
The SME we spoke with today noticed after only a couple of weeks use that some emails being sent were getting bounced back as undeliverable. Upon further investigation of the problems, it came to light that the IP range assigned by BT to the SDSL products is classed as Dynamic by a couple of RBL providers, due to the Reverse DNS (rDNS) lookup of the IP range. Conducting a reverse lookup on the IP of the BT Business SDSL lines does indeed show they resolve back to "host81-137-*-*.in-addr.btopenworld.com". Because of this rDNS issue, the SME is now finding it more and more difficult to send email out, as more and more companies are employing the use of RBLs on their email gateways.
We asked if the SME had contacted BT Business about these issues. The SME told us they had asked BT to change the rDNS entry for their IP or range, but were told BT were unable to do this. The customer then asked for the IP address of a relay server through which they could send their email via the BT SDSL email relay server. At this point, the customer was informed that only 7 domain names were allowed to relay, per SDSL connection. This meant the customer could have only added a maximum of 14 domains (due to having two SDSL lines) to the BT relay server. The problem there is that the SME in question has 104 domains that are used for email purposes. There is no mention of a seven-domain limit within the terms and conditions of the SDSL contract. The SME then went on to ask if BT could add their email server IPs as "trusted", to the BT relay server, enabling them to send email from any of their domains. Once again, BT said this was not possible.
Typically the SME in question has thus found itself stuck in a contract for a service that is not working as intended.
The I.T.Vibe piece makes for interesting reading, especially at a time when BT is desperate to promote and sell its SDSL products.
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