While it's extremely handy to insert the registration buttons macro into event announcements, recipient interaction with them isn't recorded on the email log. For example, an announcement I sent out this week has one link click recorded against it.

However, six additional bookings immediately followed the announcement. The only way to capture this data is to manually cross reference registrants registration date/time with the event announcement. The bookings clearly occurred as a result of the announcement. However, as registrations through the buttons aren't included in the tracking data it's pointless using the email log to evaluate the impact of event announcements, if number of bookings is the key outcome of the event announcement.