OS X users, if you are paranoid about using online tools for the SHA-256 hashing, you can do this from the command line with sha256deep.
Via Homebrew it'd go like this (replace the 1st step with whatever package manager you like):
$ brew install md5deep
$ echo -n my@email | sha256deep
d869524229c1e2f6139194fee1aac14f873b008dd0279458cbdfb6b3fbade1d2
$ echo -n 'my@email' |openssl dgst -sha256
d869524229c1e2f6139194fee1aac14f873b008dd0279458cbdfb6b3fbade1d2 echo -n 'my@email' | md5 $ echo -n 'my@email' | shasum -a 256
d869524229c1e2f6139194fee1aac14f873b008dd0279458cbdfb6b3fbade1d2 -MD5 is what's used in the linked spreadsheet's email address fields, which is what I thought we were talking about. SHA-256 is used in jedsmith's lists.
python
>import hashlib
>hashlib.sha256("you@yourdomain.com").hexdigest()