Cognos 10.2.2: CNC-SDS-0408 There are email messages waiting to be sent.

[Cape Cod Gunny]

We are using Cognos 10.2.2. Every now and then a scheduled report goes into a waiting state with the message "CNC-SDS-0408 There are email messages waiting to be sent."

A google search turned up this reference:
https://www.ibm.com/support/pages/cnc-sds-0408-there-are-email-messages-waiting-be-sent

I read the suggestion here which says to "Remove the user ID and password from the SMTP mail server settings in Cognos Configuration." This has already been done inside our configuration. There is no SMPT user ID or password.

This does not happen all the time. It happens intermittently. Unfortunately, I have not been able to tell "which people received the emailed attachment and which ones are still waiting to be sent.

We have this running on a Windows Server under IIS.
Is there something I can do to fix this situation or prevent it from happening?