550 Undeliverable Message Problem

[brayshay]

We use Small Business Server 2008, including MS Exchange 2007 and BT Exchange Lite Plus.  Our domain, barayshay.co.uk, is hosted by BT.  Our server sends outgoing messages correctly for my email address but all other users' outgoing email messages are bounced with the message mail.btconnect.com #550 Not permitted ##.  Does anyone have any idea why we've got this problem?

[badboyhouse]

Interesting.  I have a client with exactly the same problem - they too use SBS and Exchange.  They started to have this problem last Thursday AM. Up until that time they had no problems whatsoever.  BT must have made some changes to the domain - it's too much of a coindidence.

I reported to BT this morning who have escalated the issue to third line support.

[888SMF]

I too starting experiencing this problem around the same time. I have been using Sendblaster2 for months to regularly send newsletters to circa900 email addresses with 100% success. On 11th Jan a mailing was successful, on 14th Jan, the SMTP rejection rate to the same list was basically 50% including to my own known test addresses. If I send through a specialist SMTP service, it is successful. Something appears to have changed at BT. I have spent a long time on the phone to BT support with them even taking control of my screen to ensure all settings are correct. 

[badboyhouse]

I figured this out.

I believe BT havre retired the mail.btconnect.com and smtp.btconnect.com mail servers - effective last Wednesday. You now have to use the Office 365 settings - or send emails via DNS if you have an Exchange server.

[brayshay · Accepted solution]

Yep you're right.  I spent a couple of hours on the telephone yesterday with a really helpful guy at the BT Techncial Help desk who knew exactly what I was talking about. 

The fix for folks like us that use MS Small Business Server (SBS) is to stop using Smarthost and switch to DNS. Using the SBS wizard to configure the email connection to change the way we send outgoing email took two minutes once I was shown what to do.  Why, oh why has BT not put any kind of documentation for this fix on its web site?  I gathered that the BT Help desk has received a fair few calls like ours.

We also had to submit a formal request to BT to create a Reverse DNS; I was a bit surprised to discover BT had never set this up when we migrated our domain to BT a year ago.

Thanks for your help.