Received mail time mismatch

Recently notes client users receive mail and the mail received time is mismatch. AM become PM or PM become AM. Say a notes user send a mail to another notes user at 2:00PM.

the user receive the mail instantly and found received date 2:00AM. All users have same problem.

I checked the time zone in OS400 is Correct format with no DTS. And Server document showing, using OS system time zone.

I add a line to notes.ini TIMEZONE=+6 but no result, so again I add TIMEZONE=18 then users received mail in correct time but server time is mismatch, if i give “show time” in domino console, shows “timezone -18”. My current timezone is +6 GMT.

What shell I do. Pls help.