The previous reply is probably on the right track. The ArcRet.exe utilizes a plug-in that you have defined to decide what to do. The error you mention is coming from GenPrint - so I can assume this means you are retrieving from archive in an effort to reprint something.
In reprint, the ArcRet tries to reverse-engineer an actual batch run to the point where GenPrint can take over. So, the first step after retrieving the archive record is to recreate a NewTrn.dat file - the normal output of a Gendata run. To do this, the <Trigger2Archive> group is run in reverse to map what is in the archive record back to the NewTrn record. Afterwards, the document is loaded, and the NewTrn record is converted into a batch record where the recipient codes should have been assigned.
Now, this utility pre-dates the newer DMStudio model where the recipient codes are actually defined in the Application definition (BDF) file. Prior to DMStudio, the <Recip_Names> group in the INI would have defined these things. So it is possible that as a work-around you can define the <Recip_Names> group in the INI Something like this:
< RECIP_NAMES >
INSURED = 001,INSUREDS COPY
COMPANY = 002,COMPANY COPY
AGENT = 003,AGENT COPY
If you check your BDF out, you can probably find whatever values each recipient should define. The INI option defines the Recipient name on the left of the equals. The right side is the recip code separated from the description using a comma. If your BDF defines any other recipient properties, they are not used in this situation.