SLF, thanks for taking the trouble to reply. Unfortunately neither of these ideas will allow me to continue to receive any e-mails at all.
The originator of the offending e-mails says the following in response to complaints.
"This issue has come up before and my service providers say:
Your recipient's email client determines how to read the email received. Their email client is setup to connect to the web when reading an HTML email containing images that reside on the web.
This may not be a lot of help. But if you continue to get the problem with other emails then you can setup your email software differently to eliminate it."
The absolute solution is to be taken off the senders address list, but this isn't conducive to good business!