Can't you speak clearly?

$\begin{array} {c | c | c | c | c } \text{Person \ Letter} & 1 & 2 & 3 & 4 \\ \hline \text{Andy} & \times & & & \\ \hline \text{Brandy} & &\times & & \\ \hline \text{Candy} & & & \times & \\ \hline \text{Dandy} & & & & \times \end{array}$

Letters 1, 2, 3, and 4 were supposed to be delivered to Andy, Brandy, Candy, and Dandy, respectively. However, the delivery man made terrible mistakes and nobody got the right letter, hence the table above.

Andy and Brandy both know this, but Andy gives an additional information to Brandy by saying, "The letter I received is not $Z$ ," with $Z$ being one of 2, 3, 4. Brandy knows what $Z$ is, whereas we the readers don't.

Using only this additional information given by Andy, Brandy immediately claims that she know which letter everyone received.

Given that all of them spoke the truth, can you determine which letter did Andy receive?