Hello Tonyp. Thanks for your reply. To replicate the issue:
I selected a "View by Month" menu item type, and it shows a page like attached.
When I select email icon (see red arrow) I get a popup box where I fill in email address etc. When I then hit Send I get the Error 403 Link is missing. I can see from the popup window header that the link for mailto is there, but somehow it is not found by by joomla.
AJ