Fourier transform properties
If you already know the - quite well-known :) - FT pair $$e^{-at}u(t) \longleftrightarrow \frac{1}{a+j2\pi f}$$ then by setting $a = 1/T$, you get $$e^{-\frac{t}{T}}u(t) \longleftrightarrow \frac{1}{\frac{1}{T} + j2\pi f}$$
Time delay property $$x(t-t_0) \longleftrightarrow X(f)e^{-j2\pi ft_0}$$ can be used now by setting $t_0 = T$, and then $$x(t-T) = e^{-\frac{t-T}{T}}u(t-T) \longleftrightarrow \frac{1}{\frac{1}{T} + j2\pi f}e^{-j2\pi fT}$$
Adding your $1/T$ constant in front, you get $$\frac{1}{T}e^{-\frac{t-T}{T}}u(t-T) \longleftrightarrow \frac{\frac{1}{T}}{\frac{1}{T} + j2\pi f}e^{-j2\pi fT}$$
Finally, multiplying both numerator and denominator by $T$ you get what you want: $$\frac{1}{T}e^{-\frac{t-T}{T}}u(t-T) \longleftrightarrow \frac{1}{1 + j2\pi fT}e^{-j2\pi fT}$$