Hi All,
After many research, I'm definitely despite as I found nothing that can help me to resolve this issue.
When I want to set up an Outlook externally, the configuration failed with the following message :
'No encrypted connexion is available to your exchange server'
With https://testconnectivity.microsoft.com, everything seems to be well and good configured.
With Test-Autodiscover... cmdlet, everything is fine too.
I try to change a lot of settings into IIS or Echange but nothing change the result, always the same error.
This appends only for external users, internally everything remains good.
Thank you by advanced for your help,
Jean-Yves F.