For historical reasons, our SMTP servers allow sending authenticated email without TLS. This is insecure, and doesn't belong on the modern internet as it is possible for the username and password to be intercepted by a third party. We will no longer allow this as of the 4th of July. We are emailing customers who seem to be using insecure settings to warn them about the change. We have a support site page about what settings to change here: https://support.aa.net.uk/Enable_TLS_on_smtp.aa.net.uk Please contact support if you have any questions.