-pgg-epg.el provides no more additional features than pgg-gpg.el,
-because PGG's API is restricted so that it supports old PGP 2.x/5.x.
+EasyPG API is a superset of PGG, so pgg-epg.el just emulates the old
+behavior of pgg.el. Major features which PGG lacks are
+
+- Key selection user interface
+- Diagnosis interface to the verify operation
+- Web of trust
+- S/MIME using gpgsm
+
+** SEMI based MUA
+
+SEMI is the MIME library used by Wanderlust, cmail, T-gnus, etc.
+
+There is an EasyPG capable SEMI library called EMIKO-EasyPG. It can
+be downloaded from the same site of the EasyPG distribution point.