Sponsor S report: mention completion of A.1.4.

wiki/src/blueprint/SponsorS/reports/2015_12.mdwn

@@ -61,6 +61,10 @@ for milestone IV (2016, January 15):
    Tails. Claws Mail will be removed in the next release of Tails, version 2.0.
    Users can now use the Icedove persistence feature.
 
+## A.1.4 Provide a migration path for our users from Claws Mail to Icedove
+
+This was completed when Icedove became the default email client.
+
 # B. Improve our quality assurance process
 
 ## B.1. Automatically build ISO images for all the branches of our source code that are under active development