Dreams dictionary: Post-office
Dreams dictionary: Interpretation 1
To dream that you are in a post office signifies an important message from your subconscious or inner wisdom. It may relate to your need to reach out and communicate with others. Alternatively, the dream means that you are trying to maintain your beliefs or reestablish contact with someone from your past.
Dreams dictionary: Miller Dream Interpretation
To dream of a post-office, is a sign of unpleasant tidings. and ill luck generally.