Potentially an admission or representation in a letter signed by the party to be charged with the promise or representation sought to be enforced could be binding upon that person if it is signed and there is some thing of value possibly offered to be exchanged for the promise.If the document sent was an e mail, then the e mail was not signed in ink or in pencil. It is simply an electronic transmission. If you never signed a written deed (usually before a notary public), it would appear from the facts you state in your question that the promise made in the e mail that was sent has no legal effect.Good luck.