We are investigating an intermittent problem sending email via our webmail service and directly from their normal email programs
We are seeing low levels of packetloss, but only on IPv6 - we are disabling IPv6 on smtp.aa.net.uk for the moment to see if that makes a difference whilst we investigate further.
IPv6 was a red herring - we're still investigating this intermittent problem.
This problem is occurring when trying to send messages to email accounts that are hosted on Office 365 / outlook.com servers. This is related to https://aastatus.net/2502
Our mail servers should handle the type of failure better, we are looking at improving this.
Routing is now working again, we believe the problem is due to to routing through one of our routers which we have disabled this evening. We are still investigating the actual root cause of this. We would like to thank the other customers who reported this fault to the Office365 help desk, and do apologise for the frustration and inconvenience this has caused.