Unable to authenticate your credentials

Error description:

Connect-MsolService : Unable to authenticate your credentials. Make sure that y
our user name is in the format: @. If this problem persists,
contact Support.
At line:1 char:20
+ Connect-MsolService <<<<
    + CategoryInfo          : OperationStopped: (:) [Connect-MsolService], Mic
   rosoftOnlineException
    + FullyQualifiedErrorId : 0x80048862,Microsoft.Online.Administration.Autom
   ation.ConnectMsolService

Symptoms:

you cannot telnet to the following IP address:

telnet 157.55.59.213 443
Connecting To 157.55.59.213...Could not open connection to the host, on port 443
: Connect failed

Solution:

Make sure you can connect to 157.55.59.213 on port 443 (https) probably your company is using a proxy for access to the internet.

telnet 157.55.59.213 443

To make this possible, you can for example configure a proxy in netsh:

netsh
netsh>
netsh>winhttp
netsh winhttp>set proxy .......