I have a problem on the listed devices!
Lumia 950 (no windows insider) 10586.164 windows 10
Lumia 1020 windows 8.1 last update
Lumia 925 windows 8.1 last update
Lumia 820 windows 8.1 last update
I've done all and the problems still exists;
-synchronized outlook (settings, email+ac... ) error 0x80070490
-soft reset error 0x80070490
-remove the battery (not on lumia 1020 and 925) error 0x80070490
-I did a hard reset, and afther all good (apps, mails...), contacts sync error 0x80070490
So, last hope is WDRT (windows device recovery tool), ok! I tried that, with all my devices, and start from beginning... region, user mail, password... on all my lumias!!! Synchrnized all... apps, mails.. but contacts still have same error code 0x80070490.