It still is, as of the latest version. Messages can be edited or deleted up until the point where they've been read. Then they're moved from your 'outbox' to a

It still is, as of the latest version. Messages can be edited or deleted up until the point where they've been read. Then they're moved from your 'outbox' to a 'sent' folder. I'm not entirely certain of what my opinion on this sort of thing really is.