I created a new single risk event and set the damper to Auto as the other options were 20 min, 30 min, 1 hr, 1.5 hr etc.
I then put Eicar on my system and got the popup notification about 30 seconds later and got the email 3 minutes later.
I then put it on my system again and got the popup right away and still never got the email after an hour.
EDIT
I got the email exactly 1 hour after the first one, so it seems that Auto is one hour.
Still even the best is 20 minutes which is not very helpful if we get attacked by a virus and it is spreading accross the network