diff --git a/libretroshare/src/gxstrans/p3gxstrans.cc b/libretroshare/src/gxstrans/p3gxstrans.cc
index 216be1f18..6f12b240d 100644
--- a/libretroshare/src/gxstrans/p3gxstrans.cc
+++ b/libretroshare/src/gxstrans/p3gxstrans.cc
@@ -20,7 +20,7 @@
 #include "gxstrans/p3gxstrans.h"
 #include "util/stacktrace.h"
 
-#define DEBUG_GXSTRANS 1
+//#define DEBUG_GXSTRANS 1
 
 typedef unsigned int uint;
 
@@ -183,6 +183,10 @@ void p3GxsTrans::handleResponse(uint32_t token, uint32_t req_type)
 
 			const RsGroupMetaData& meta = grp->meta;
 			bool subscribed = IS_GROUP_SUBSCRIBED(meta.mSubscribeFlags);
+
+			// if mLastPost is 0, then the group is not subscribed, so it only has impact on shouldSubscribe.  In any case, a group
+			// with no information shouldn't be subscribed, so the olderThen() test is still valid in the case mLastPost=0.
+
 			bool old = olderThen( meta.mLastPost, UNUSED_GROUP_UNSUBSCRIBE_INTERVAL );
 			uint32_t token;
 
@@ -190,8 +194,9 @@ void p3GxsTrans::handleResponse(uint32_t token, uint32_t req_type)
 			bool shouldUnSubscribe = false ;
 			{
 				RS_STACK_MUTEX(mDataMutex);
-				bool shouldSubscribe   = !subscribed && ( !old || meta.mGroupId == mPreferredGroupId );
-				bool shouldUnSubscribe =  subscribed &&    old && meta.mGroupId != mPreferredGroupId;
+
+				shouldSubscribe   = (!subscribed) && ((!old)|| meta.mGroupId == mPreferredGroupId );
+				shouldUnSubscribe = ( subscribed) &&    old && meta.mGroupId != mPreferredGroupId;
 			}
 
 #ifdef DEBUG_GXSTRANS
diff --git a/libretroshare/src/gxstrans/p3gxstrans.h b/libretroshare/src/gxstrans/p3gxstrans.h
index 20b8ee4c0..9c0a8f999 100644
--- a/libretroshare/src/gxstrans/p3gxstrans.h
+++ b/libretroshare/src/gxstrans/p3gxstrans.h
@@ -150,12 +150,12 @@ public:
 	/// @see RsGenExchange::getServiceInfo()
 	virtual RsServiceInfo getServiceInfo() { return RsServiceInfo( RS_SERVICE_TYPE_GXS_TRANS, "GXS Mails", 0, 1, 0, 1 ); }
 
-	static const uint32_t GXS_STORAGE_PERIOD = 0x127500;	// 14 days.
-	static const uint32_t GXS_SYNC_PERIOD    = 0x127500;
+	static const uint32_t GXS_STORAGE_PERIOD = 15*86400;	// 15 days.
+	static const uint32_t GXS_SYNC_PERIOD    = 15*86400;
 private:
 	/** Time interval of inactivity before a distribution group is unsubscribed.
 	 * Approximatively 3 months seems ok ATM. */
-	const static int32_t UNUSED_GROUP_UNSUBSCRIBE_INTERVAL = 0x76A700;
+	const static int32_t UNUSED_GROUP_UNSUBSCRIBE_INTERVAL = 16*86400; // 16 days
 
 	/**
 	 * This should be as little as possible as the size of the database can grow