Once we have an update we will post it here.
Update 16:45 Services are now restored.
Sorry for the interruption, we will investigate the issue to find the root cause
As part of our transition of our Hosted Exchange plans to Exchange 2010, we have had to whitelabel the autodiscovery service of existing Exchange 2007 customers.
Customers may receive a pop up warning them that https://exch2007.exchangehosting.eu/autodiscover/autodiscover.xml is trying to reconfigure their email settings in Outlook. This is normal behaviour and can be allowed.
Note: Hosted Exchange customers are reminded that if their DNS hosting is not using ns1.blacknight.com and ns2.blacknight.com then they must manually configure an autodiscover subdomain as follows: if your Hosted Exchange domain is domain.tld, then you must create a subdomain of domain.tld called autodiscover.domain.tld which must be created as a CNAME to autodiscover.blacknight.com

As part of our ongoing commitment to bring you the latest in technology improvement, and as part of our overall transition to Exchange 2010, over the next 2 weeks we will be upgrading our Hosted Exchange platform to Exchange 2007 Service Pack 2.
As we designed the Hosted Exchange platform from the beginning to be completely resilient, there will be no downtime evident to Exchange users during this major upgrade.
At 23:00 (Irish time) tonight, Wednesday 12 August, we will be performing some essential maintenence on the Client Access servers in our Hosted Excange platform.
The only things effected will be client access to the platform - Outlook/Entourage/Outlook Anywhere/POP/IMAP. Mail will flow as normal during this window.
This maintenence window is for 10 minutes.
UPDATE: Apologies for not updating this sooner. The maintenance was conducted last night without issue