The Lake House (2006)

Romantic fantasy starring Keanu Reeves and Sandra Bullock. Kate Forster (Bullock) is a doctor who lives in a beautiful home by a lake. 
Forced to move elsewhere, she requests that any correspondence that arrives at the lake house be passed on to her new address. 
To her surprise, she soon receives a romantic note from Alex Burnham (Reeves), an architect who lives in the cottage she once called home. 
However, a look at the postmark on the letter reveals that he lived at the home two years before she did, and that somehow they've come in contact with one another through a space in time.