Error Editing Synchronized users

Question

I have users synchronized from On-Premise to Exchange Online. When I try to update three of them, I get an error. 

 The error is: The properties on this object have invalid data. If you click OK default values will be used instead and will be saved if you do not change them before hitting Apply or OK on the property page.

But even if I hit okay email address section is left blank and I get another error: 

Some controls aren't valid. 

ExternalEmailAddress is mandatory on MailUser 

The mail contact and email user must have a valid external e-mail address.

But when I try to add the email address I get an error saying it already that email address.

The user can get mail but I cannot update any information. 

Please help

Answer 1

Hello Roland,

Had you referred to my reply? Feel free to let us know your update.

Thanks for your time.

Regards,

Rudy

Answer 2

Hello Roland,

For better understand your scenario, may I collect a video about the whole issue reproduce steps please? And, it will benefit us to analyze this issue. We had sent you a private message to collect it.

Meanwhile, we suppose that you are in the hybrid environment, so you need to update the Exchange related properties from the on-premises Exchange server side or the user account related information from Local AD side. Can I know if any specific characters in those users' setting please, like  "@"? You may go to local Exchange server and AD to check it.

Looking forward to your update.

Regards,

Rudy