Why does the following define a distribution and of which order?

Question

I want to show that $$\phi\mapsto\underset{\varepsilon\searrow 0}{lim}\int_{-\infty}^{\infty}\frac{\phi(x)}{x+i\varepsilon}dx$$ defines a distribution on $\mathcal{D}(\mathbb{R})$ but I just don't come up with a good idea to show that. Second part would be to determine the order of it. Thanks for any suggestions.