We were using a very old version of phpList. Perhaps the chief reason for using phpList is that it enabled us to send the same email every day to the whole list. (The emails contained links to places on a website which changed each time a person visited them, so that they read the next item in the series.)
This behavior seems to be blocked in the current version of phpList.
What can I do to work around this blocking in order to achieve what we originally chose phpList for.