As a follow-up, I just completed a non-case-sensitive search for "ImapRetrieval" in all files located under C:\Program Files (X86)\SmarterTools.
I found a bunch of occurrences of "ImapRetrieval", including "<imapRetrievalDownloadPath>d:\SmarterMail\ImapRetrieval\</imapRetrievalDownloadPath>".
I did not find any reference to "C:\SmarterMail\ImapRetrieval". This makes me think it might be encoded within an EXE, DLL, or some other type of file.