Wikipedia:Canvassing

In general, it is perfectly acceptable to notify other editors of ongoing discussions, provided that it be done with the intent to improve the quality of the discussion by broadening participation to more fully achieve consensus.

Canvassing is notification done with the intention of influencing the outcome of a discussion in a particular way, and is considered inappropriate. This is because it compromises the normal consensus decision-making process, and therefore is generally considered disruptive behavior.