Can't send emails after email server certificate updated
The certificate on our in-house hosted Exchange server was updated and now the Thunderbird users can't send emails. Appleail users and iPhone and Android email clients can send mail. The Thunderbird users can receive mail, but when sending, we get the message "Sending of the message failed. An error occurred while sending mail: Unable to establish a secure link with Outgoing server (SMTP) post.samuels.org using STARTTLS since it doesn't advertise that feature. Switch off STARTTLS for that server or contact your service provider." We have tried deleting the certificate and rebooting and then adding the new certificate. We have tried setting the security to SSL/TSL and none, but still couldn't get emails to send. Our IT contractors tried a lot more things.