Although there are a significant number of special issues alerts as you can check : https://www.google.com/search?q=conferences+alert
, but i don't highly recommend to subscribe to any of them. I have tried most of them for some time. They have missed many prestigious conferences or journals.
As my research field is electrical and computer engineering, I always prefer to follow directly IEEE or IET at http://www.ieee.org/conferences_events/index.html and http://www.theiet.org/events/
Otherwise google is the best source to find any call for special issues at your relevant field.