We are looking to send email via Office 365, however we are unable to send email via SMTP authentication as Progress doesn’t support STARTTLS. Is this something we can request for a future version and is this something you may be aware of already?
STARTTLS is an older way of having email servers switch from clear text over to a TLS connection without reinitializing a socket connection. This is done for compatibility with older clients that do not support STARTTLS. The server could support both cleartext and TLS on the same network port. The ABL network socket support does not allow switching from cleartext to TLS after a connection has been established.
By default exchange online uses "opportunistic encryption"...e.g. STARTTLS.
But you can change the connector configuration to use pure TLS. They term this "forced TLS".