jmc

The expression $\frac{n+6}{n}$ can be simplified as $\frac{n}{n}+\frac{6}{n}$, or $1+\frac{6}{n}$. So in order for this expression to have an integral value, 6 must be divisible by $n$. Therefore, the sum of all positive integral values of $n$ is just the sum of all the divisors of $6$. Since the prime factorization of 6 is $2\cdot 3$, we know that 6 is only divisible by 1, 2, 3, 6, and the final answer is $1+2+3+6=\boxed{12}$.