A contract (including a lease of real property) is formed when an offer is accepted.
First there must be an offer that is capable of acceptance. It must be an actual offer and not an invitation to treat or an option, it must be made to the person who purports to accept it (e.g. an offer made to Fred can't be accepted by Anne), it must be communicated to that person and it must not have been revoked.
The offer must be accepted. Such an acceptance:
- must be in reliance of the offer
- must be complete and unqualified
- conditional assent is not acceptance
- must be clear and certain
- may be express or implied
- may be retrospective
- a counter-offer is a rejection of an offer
- must be communicated (unless this has been dispensed with and conduct is acceptable communication)
- in accordance with any method prescribed by the offeror (e.g. if the offer must be accepted by post an email is not acceptance)
Looking at the linked back-story, what Eric sent you was clearly an offer. However, you never accepted it. There is no communication between you and Eric along the lines of "I'll take it" so there is no contract. Further, the offer was withdrawn so you cannot now accept it.