Douglas Henwood wrote:
When I click on links in emails from mailing lists, I usually get an error message like this. I have to copy the link into Chrome to get it to work. Why? Is this some security setting run wild? It's from a trustworthy source.
https://discussions.apple.com/content/attachment/69e33a57-480d-4e91-968d-7d673e79728a
Verify you have Safari set as your default browser to test and compare your results.
other possibilities
Open Mail.app select Mail>Preferences>Privacy disable “Protect Mail Activity” / “Hide IP address” / “Block all remote content” —content for the email will load automatically
if no insight or resolve
Check or change network settings…> System Preferences > Network > select your Network in the left column > Advanced > Proxies > disable/uncheck Auto Proxy Discovery.
also known issues involving 3rd party anti-virus preventing iCloud mail from loading content in Apple Mail
ref: icloud mail content invisible in 12.0.1 - Apple Community
If you see 'Unable to load remote content privately' at the top of ...
If you see 'Unable to load remote content privately' at the top of an email - Apple Support
uninstall third party Anti-virus software is also known to effect Mail in a negative way...