"The meeting was postponed until next week." - simple past passive of "postpone". "The meeting will be postponed until next week" - uses the past participle of "postpone" as an adjective describing the meeting. The difference is that the first one talks about a past action; the second about the present status of the meeting. So you could say "The meeting was postponed until next week, but now we have decided to have it tomorrow". But you couldn't say "The meeting will be postponed until next week, but now we have decided to have it tomorrow" because "The meeting will be postponed until next week" already describes the current plan.

Both are fine. The tense differs.

In my opinion, both sentences are correct in grammar. However, they do have difference in the meaning. I try to make it easier to be understood using scenes. For example, there should be a meeting holding in this afternoon. 1. The meeting was postponed until next week. This sentence can be used, if a official notification has been made some time before and you are now sure that the meeting will not be held until next week. It used a past tense as the informing of "Postpone" is happened. 2. The meeting will be postponed until next week. If this sentence is used, then the situation could be: You knew from some unofficial sources that your boss is planing to hold the meeting in next week, but he has not yet informed you and your colleagues formally, which equals to "The date is to be decided" in official occasion (But you know that he is going to make the notification.) Then, the "Postpone" is now a future tense, as it has not been informed and there is a possibility that the informing will not be happened ( if the boss changed his mind). Hope these help. =)

Hi Leelee. In 1) The meeting has already been postponed. In 2) The meeting has not been postponed, but has now been postponed, as of right now.