Hi,

I have recently encountered something similar. Everything seems to be working fine, and no errors are being reported. Here's what I did:

1. Enable host server logging

2. Send a SmartAction reply again

3. Check latest HostServer log. Found an entry with a warning about spam. Turns out there is no error reported because this is not an error.

4. Followed the guide here to disable spam security. I added the following in my K2HostServer.exe.config, and restart K2 blackpearl service:

<system self="K2:DENALLIXK2Service" enableListeners="true" allowAmbiguity="true">

        <security spamSecurity="Off"> <!-- Default is InternalMail. -->

          <!-- A list of trusted domains that are checked against the RECEIVED-FROM header. -->

          <authorizedDomains>

            <add domain="*.denallix.com" />

          </authorizedDomains>

        </security>

    </system>

You may want to play around with the spam security settings so that it meets your security requirements.

Thanks. No error related to the smartaction is found. 

I found that there is Standard - Exchange Integration Permission error after running analysis. I posted another post as well. Do you face that same issue?

http://community.k2.com/t5/K2-blackpearl/Standard-Exchange-Integration-Permissions/m-p/95963#M30984 

Thanks again.