Scenario:

When trying to send data to CitiBank (Opentext's AS2 solution) via EXTOL Secure, we receieved the error: HTTP/1.1 404 Not Found

Issue:

ESX Server log: Established connection(cas2-citi.ms.gxs.com:443)
Sent HTTP request
Received HTTP response

HTTP/1.1 404 Not Found
Server: Apache-Coyote/1.1
Transfer-Encoding: chunked
Date: Mon, 12 Oct 2015 12:24:35 GMT

Resolution:

Contact AS2 partner, Opentext in this case, to discuss why error is happening. Based on the server logs, we show we are able to connect to their AS2 server, however the Opentext AS2 server throws the exception error: HTTP/1.1 404 Not Found

When we contacted Opentext, we were told we needed an 'expanded' url: https://cas2-citi.ms.gxs.com/enterprise/as2