How to calculate Sum of a function over a list


tlist = Table[i, {i, 1, 10}]

tlist:{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

f = E^(-((2 t)/T));

Sum[f, {t, {tlist[[i]], {i, 1, 8}}}]

How to calculate Sum of a function over a list?

One way to do this is by defining f[t_]:= E^(-((2 t)/T)); Is there a way to do it in any other manner. Because I have to do this for various functions with a higher level of complexity.