--- CMakeLists.txt
+++ CMakeLists.txt
@@ -20,6 +20,7 @@
 include_directories(${PROJECT_SOURCE_DIR}/src/services)
 include_directories(${PROJECT_SOURCE_DIR}/src/services/gmail)
 include_directories(${PROJECT_SOURCE_DIR}/src/services/outlook)
 include_directories(${PROJECT_SOURCE_DIR}/src/services/imap)
+include_directories(${PROJECT_SOURCE_DIR}/src/services/pop3)
 #
 # Source files