Configuration of Mail Dispatch with STARTTLS raise error LIBS-1803, what configuration we did wrong?

Fri, 26 Jan 2024 11:57:10 +0000

we are trying to setup the mail dispatch for our customer Fondation Patrimoine, the customer gave us the following configuration :
smtp : smtp.office365.com
sécurity : STARTTLS
Port : 587

So we configure it like this

but we get the following error

Connecting to SMTP Server "smtp.office365.com"
12:52:19> <Emails are not allowed> --> To:Emails are not allowed|Cc:|Bcc:|Subject:"Test Sending Email"
12:52:19> Error: Sending Internet Mail Failed: LIBS-1803 Unable to send the message with subject: "Test Sending Email"
SSL negotiation failed.

In the "Internet Option", TLS1.2 and TLS1.3 are activated

Does anybody encountered this error ?
Does STARTTLS supported by MailDispatch ?

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Configuration of Mail Dispatch with STARTTLS raise error LIBS-1803, what configuration we did wrong?