I send regularly HTML mail with links to pictures.
In most tools to read emails: Mail for OS x, Browsers with Yahoo/Hotmail etc
I can change the pictures on my server and those changes are reflected in what the recipient sees whenever she
reloads the message.
Entourage:mac v. X however caches and shows old pictures.
I have tried without success:
1.Rebuild the Entourage Database (not that I would like to impose that on the recipients of my emails)
2. Include <META HTTP-EQUIV="refresh" CONTENT="15">