We've updated the security settings on the non-default SMTP port 26 on Gimli to be restricted only to authenticated access, and allowing for a larger message size.  This is how we have most/all of our servers configured, this change makes Gimli behave as our other servers do.

Customers may use port 26 for SMTP to bypass restrictive ISP firewalls and to send larger-sized messages.   The security setting prevents email from arriving on this port, allowing only customers to connect.