README.md in isolator-0.1.0.pre vs README.md in isolator-0.1.0.pre2

@@ -106,9 +106,10 @@
 
 Isolator has a bunch of built-in adapters:
 - `:http` – built on top of [Sniffer][]
 - `:active_job`
 - `:sidekiq`
+- `:mailer`
 
 You can dynamically enable/disable adapters, e.g.:
 
 ```ruby
 # Disable HTTP adapter == do not spy on HTTP requests