Have I read the related troubleshooter articles above before posting (which pages?)? No
Have I searched the forum before posting? Yes / Not in depth
Have I read the documentation before posting (which pages?)? No
Joomla! version: 1.5.25
PHP version: 5.2.17
MySQL version: n/a
Host: Apache / GreenGeeks hosting
Akeeba Backup version: Version before current (already manually updated)
------------
Most of above is not applicable to this. I had two sites, one on Godaddy, one on GreenGeeks. Godaddy site allowed a one-click login and backup from the email notification, whereas the GreenGeeks site did not.
I'm almost 100% certain this is due to GreenGeeks running "Mod Security" on all hosted domains (unless specifically asked not to). I've had problems with running CiviCRM (a very large Joomla component), and your one-click link appears very similar to ones that caused problems (i.e. triggered the mod security code).
So, this is just an informational posting, in case you're interested in seeing if you can change your link parameters to avoid getting blocked.
I'm not sure, but perhaps changing it so that the long parameter was enclosed in string markers, etc.
I'd be willing to work with you or introduce you to their support department
Stephan