lib-storage: Updated MAIL_SEARCH_ARG_FLAG_USE_TZ comment.

diff --git a/src/lib-storage/mail-search.h b/src/lib-storage/mail-search.h
index e0a9fd0aa2d37b06749ea0948c21f66bab1e1896..a21e9cd6bb1ec1fc5eecc2bba342880f6f3fcf83 100644 (file)
--- a/src/lib-storage/mail-search.h
+++ b/src/lib-storage/mail-search.h
@@ -53,8 +53,22 @@ enum mail_search_date_type {
 };
 
 enum mail_search_arg_flag {
-       /* For BEFORE/SINCE/ON searches: Don't drop timezone from
-          comparisons */
+       /* Used by *BEFORE/SINCE/ON searches.
+
+          When NOT set: Adjust search timestamps so that the email's timezone
+          is included in the comparisons. For example
+          "04-Nov-2016 00:00:00 +0200" would match 4th day. This allows
+          searching for mails with dates from the email sender's point of
+          view. For received/saved dates there is no known timezone, and
+          without this flag the dates are compared using the server's local
+          timezone.
+
+          When set: Compare the timestamp as UTC. For example
+          "04-Nov-2016 00:00:00 +0200" would be treated as
+          "03-Nov-2016 22:00:00 UTC" and would match 3rd day. This allows
+          searching for mails within precise time interval. Since imap-dates
+          don't allow specifying timezone this isn't really possible with IMAP
+          protocol, except using OLDER/YOUNGER searches. */
        MAIL_SEARCH_ARG_FLAG_USE_TZ     = 0x01,
 };