Just updated to the latest version of ADE - wish I hadn't bothered. The new version doesn't recognise the Adobe authorisation. I deleted the old authorisation and re-authorised (not a straightforward process as there is little information available - and none at all within the program menus). Then I connected my Sony reader to the Sony software, only to be told that the authorisation on the reader was different, and I could not transfer my library book across to it. I had to reconnect the Sony to ADE, de-authorise the reader and re-authorise it. I then still couldn't read the book, and I had to download it again from the public library. In the process I noticed that my reader was still using my old email address on its authorisation (which has been working happily for several years).
When I contacted Adobe several years ago - on changing my email address - I was assured that an Adobe ID was based on the number, not the email address, but it appears that all devices use the email address first and foremost. Luckily I have never bothered buying any books - just have the many free books that came with the reader, and library books. If I had had a load of purchased books and found I had to download them all again I would have been livid.
This just isn't good enough. A company as large as Adobe should be able to create an update to a program that finds the registration details from the previous version, without expecting the user to faff about. Also, if they say an ID is based on the unique number, then that is what they should use - not the email address - for checking validity. The whole system is a shambles, and Adobe should be ashamed of the dire quality of their products.
To add insult to injury is now impossible to send an email to Adobe - you just get page not found if you try the Contact Us page. ILLEGAL in the UK I should point out - it is a legal requirement for anyone selling from a website in the UK to have a valid email address to allow customers to contact you. SORT IT OUT ADOBE!!