Lease Still Valid?

Well, at least in California, if NOTHING is signed after the original lease runs up and you still occupy the house, it automatically reverts to a month-to-month situation. You are only required to give a 60 day notice and the landlord is only required to do the same if they want you to vacate (although I've seen many landlords accept or impose a 30 day notice).
If there is no lease, no contract, either protecting you or binding you through a certain date, it's month to month.
....At least in California.

Best wishes.

I don't think an email is enough to obligate you to a one-year lease. My landlord sends me a new copy of my lease every year to be signed and initialed. This is a legal document.

Here is a rental hotline run by the city of Mpls that might be able to answer your question: http://www.homelinemn.org/

A lease is a binding contract. If you have not signed a new form in 2 yrs you are not legally bound to any terms. Now they can try and fight it. BUT if it gets to court, no judge would ever hold you responsible.
They can be ugly and refuse to return your deposit and you would have to fight to get it back. BUT I say, be upfront. Tell them what's going on.
Dear Landlord, We have enjoyed living at (insert address). At this time this letter is to inform you of our intent to purchase our own home. We will give a 60 day notice to vacate as soon as we have purchased our home and know the exact move out date.
We would like to make arrangements to walk the townhome with you and discuss your move out procedures and expectations.
We appreciate your understanding and look forward to smooth transition in our next home.
If you have any questions, please let me know.
Sincerely
That way nothing is dropped on them and you both know what to expect
Good luck and GOD BLESS!
D.

from my knowledge in this buisness for a long time-your original lease is no longer binding-however i would contact the landlord and let them know your looking to buy a house-so you will continue to do a month to month.here on this property each yr a new lease is signed-if they dont and go to month to month its an extra 75.00 added to their rent.the best way to handle this is just by talking to landlords.

You'll need to check the state laws, but I don't see how an email would ever count in place of an actual wet signature. Why don't you just call your landlord & ask them what their thoughts are?

Did you sign a lease extension? As in, did the email contain a lease extension in it? All states are different, but no matter what your lease says, state law trumps a lease. So, I would look up your landlord/tenant laws in your state. Also, I would not mention it to your landlord you are leaving. Once you sign a contract on a home it will typically take 45 days to close. So, Once your offer is accepted you can then drop your notice. Also note, a 30/60 notice to vacate is by the 1st of the month, 60 days from when you drop it. My state only required a 30 day notice to vacate. I required a 60 day notice from my tenant, but if she chose to give me only 30 days I would be required to accept it. Most landlords are accepting of the fact you want to purchase a home and won't make trouble for you.

I believe it has to be in writing. I am unsure if e-mail would be binding. I think you would officially have to sign on for a new lease.

I am not sure what the laws are in your state, but in Texas, if there is no signature on an actual lease contract, you are considered a month to month tenant.