Hello,
when we configure our Domino servers (version 8.5.3) for secure SMTP sessions using STARTTLS according to this documentation
http://www-01.ibm.com/support/docview.wss?uid=swg21108352
almost all mails are not being delivered anymore except some single mails (no idea, why those were delivered but the majority not). At the moment we have no TLS or certificates installed which we will get through a third party vendor. Anyone has got an idea, what may cause this issue? Thank you in advance.