Synchronizing folder The remote server returned an error: (400) Bad Request

I installed the latest version of emclient and setup a new account. It successfully authenticated to the Exchange server but then the mail folders did not populate with mail.
I get the errors:  Synchronizing folder ‘mail account/example folder/’ failed due to the following error: The remote server returned an error: (400) Bad Request

From the logs:
11:11:01 AM   MailExceptions.OperationException: Synchronizing folder ‘john@XXXXX.com/Inbox/’ failed due to the following error: The remote server returned an error: (400) Bad Request. —> System.Net.WebException: The remote server returned an error: (400) Bad Request.

I tried on 2 different PCs and 3 different mail accounts.

Hello John,
do you have any other accounts set up that work? If not, can you try making an exception for eM Client in your Firewall and Antivirus software?
Also, which version of eM Client are you currently running? (Help>About section)

Regards,
Olivia

Have ruled out firewall and antivirus as the problem. Using the latest version. Downloaded copy this week.

Hello John,
are you able to access your mail through webmail in Internet Explorer?

regards,
Olivia

Yes. Can access through webmail, and with other mail clients such as Outlook and Mac Mail. I am having problems only with Emclient.

What mail protocol does this account use? IMAP/POP/Exchange?

Regards,
Olivia

Exchange

Hi John,
can you send me the address to the server that you are trying to connect to?
If you do not want to share it on the forum, contact me at rust@emclient.com with a link to this forum topic.

Regards,
Olivia

ews.mail.us-west-2.awsapps.com

Hi John,
can you check with your mail provider if that is the correct address to connect to?
When I try to check the connectivity to this server it tells me that it is not available and ends on timeout errors.

Regards,
Olivia

I copied it right out of the mail server settings of my Mac Mail client. So yes, it is the correct server. The mobile server is mobile.mail.us-west-2.awsapps.com

any fixes?