Due to the situation where some emails sent from Leon server were rejected as SPAM by the recipient's server, we have had to change the configuration of sending emails from Leon.
Leon server was sending an email (i.e. Handling Requests) on behalf of the client straight to the recipient's server (i.e. Handling Agent). Some SPAM filters treated an email sent from Leon, where 'From' was a client's email address, as a SPAM email and the information was never arriving to handling agent's email account.
Leon sends emails with 'From' appearing as Leon Software, so that all emails can arrive safely to recipients.
It is possible to configurate settings, so that when an email is sent, 'From' is displayed as client's email address.
In order to do that, we need an email sent to firstname.lastname@example.org with the information of access data to the SMTP server: user name & password to log in to server SMTP and email address that should be displayed as 'From' when emails are sent out.