Linux
echo joe.smith@aol.com | shasum -a 256 --> d6220b1b3a4a67731d5ca82c101cec2c30069ed674c04576e78322c1fbca1c92  -

Use -n to prevent echo from including invisible newline character:

echo -n joe.smith@aol.com | shasum -a 256
4d1612632ab95a0dec3d27f521d2b91cabe9e72a6b1ecdb8784e1ed6f3a93604  -