I'm using exim and have done nothing special to configure exim's timezone handling. When it delivers to a mbox-format file, it writes the separator line at the the beginning of the message with the local time and no timezone. This seems to be wrong. According to RFC4155's specification of the "default" mbox format, this should be in UTC (with no timezone marker). Indeed squirrelmail using imap reports this time incorrectly.
So I guess I should get exim to use UTC for that line, except that the mailutils "mail" program uses the time from there unaltered. If imap thinks that this line is in UTC, shouldn't mail think that also and convert it to local time before displaying it? Ken