The customer noticed that after migrating to a new SMP Server, there were some packages on the package server, mostly plug-ins, that are in a retrying download status and have an old, now non-existent, SMP server as the source to download from.
ITMS 8.6, 8.7
The affected packages had bad references (an invalid path) from their previous environment. Either, the package was pointing to an invalid share that contained the old SMP server name, or the actual package path had a different structure on the new SMP Server.