  Let $R$ be a commutative ring with unity, $M$ be a unitary $R$-module and $G$
a finite abelian group (viewed as a $\mathbb{Z}$-module). The main objective of
this paper is to study properties of mod-annihilators of $M$. For $x \in M$, we
study the ideals $[x : M] =\{r\in R | rM\subseteq Rx\}$ of $R$ corresponding to
mod-annihilator of $M$. We investigate that when $[x : M]$ is an essential
ideal of $R$. We prove that arbitrary intersection of essential ideals
represented by mod-annihilators is an essential ideal. We observe that $[x :
M]$ is injective if and only if $R$ is non-singular and the radical of $R/[x :
M]$ is zero. Moreover, if essential socle of $M$ is non-zero, then we show that
$[x : M]$ is the intersection of maximal ideals and $[x : M]^2 = [x : M]$.
Finally, we discuss the correspondence of essential ideals of $R$ and vertices
of the annihilating graphs realized by $M$ over $R$.
