Help! Alfresco Community 4.2.0 unable to send email invitations using new browsers

[Vhox]

Hi,

we have an old version of Alfresco 4.2.0,  (in February we will migrate to new Alfresco version), when we try to invite a new member to a site with a new version of internet browser we fail and the error i can read in alfresco.log is:

ERROR [org.alfresco.repo.action.executer.MailActionExecuter] Failed to send email to pippo@gmail.com
org.springframework.mail.MailSendException: Failed messages: javax.mail.MessagingException: Unknown encoding: ${mail.header}; message exception details (1) are:
Failed message 1:
javax.mail.MessagingException: Unknown encoding: ${mail.header} ... ... ...

No problems detected using an old browser like Chrome 106.0.5249.61 or  Firefox 85.0.1 ... any idea please?

Thanks