Feeds

T-Mobile 'fesses up to secure email ban gaffe

Wild spam-hunting robots killed off SMTP connections

Next gen security for virtualised datacentres

T-Mobile was caught blocking the secure transmission of emails earlier this month, and VPNs too, but the operator claims the former was a mistake while the latter is a legacy from a bygone era.

The problem turned up around the end of December when some punters found T-Mobile was responding to all encrypted SMTP connections, other than to its own servers, with a reset (RST) packet. That was then compounded into conspiracy when Mike Cardwell realised his Virtual Private Network connections weren't being let though either, which turns out to be an unrelated and unfixed issue.

T-Mobile employs a variety of techniques to make sending spam over its network difficult, including blocking connections made to arbitrary SMTP mail servers. Secure connections, which are then generally authenticated with a name and password, are permitted as they're useless to spammers, but for a week or two T-Mobile's network was rejecting secure connections as well as the insecure ones.

Before the age of spam one could connect to any mail server, anywhere, and ask it to relay messages, but these days servers won't accept mail unless it's addressed to someone it's responsible for, or comes from a trusted connection (so you can send mail through your own ISP's server addressed to the rest of the world). But a spammer can still connect to the mail server at, say, AOL, and send thousands of messages to AOL accounts, and if they did that from a pre-paid mobile number then they're effectively untraceable.

AOL's server may decide not to forward those messages, and may reject the connection as suspicious, but that's beside the point.

These days most mail servers allow account holders to connect remotely and send mail, therefore relieving them of the need to run a local server, but that means sending the account name and password which should only be done over a secure connection, and it's those connections that T-Mobile was erroneously blocking.

When it comes to VPNs things are slightly more complicated. T-Mobile used to sell connections which did not permit the use of a VPN, and customers on those contracts will still find their VPN use blocked. These days the operator tells us that all its mobile broadband offerings permit VPN connections, though that right may be withdrawn from a customer who abuses the fair-use policy.

So, on T-Mobile's network, secure SMTP should work, and for most people VPNs should work too, but a failing VPN is probably down to an old contract. So give T-Mobile a bell and ask before you start breaking down the packets or accusing anyone of turning Blighty into communist China. ®

Next gen security for virtualised datacentres

More from The Register

next story
6 Obvious Reasons Why Facebook Will Ban This Article (Thank God)
Clampdown on clickbait ... and El Reg is OK with this
So, Apple won't sell cheap kit? Prepare the iOS garden wall WRECKING BALL
It can throw the low cost race if it looks to the cloud
EE fails to apologise for HUGE T-Mobile outage that hit Brits on Friday
Customer: 'Please change your name to occasionally somewhere'
Time Warner Cable customers SQUEAL as US network goes offline
A rude awakening: North Americans greeted with outage drama
Shoot-em-up: Sony Online Entertainment hit by 'large scale DDoS attack'
Games disrupted as firm struggles to control network
We need less U.S. in our WWW – Euro digital chief Steelie Neelie
EC moves to shift status quo at Internet Governance Forum
BT customers face broadband and landline price hikes
Poor punters won't be affected, telecoms giant claims
prev story

Whitepapers

5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Backing up Big Data
Solving backup challenges and “protect everything from everywhere,” as we move into the era of big data management and the adoption of BYOD.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?