Wrap call or code with Meteor.defer() (same as Meteor.setTimeout()with value of 0) to allow the method to continue executing without waiting for the task to fully complete.
Meteor.defer(function(){
Email.send({
from: "hello@todoapp.com",
to: follower,
subject: "New todo added",
text: "here's the todo item: " + title
});
});
Source: https://bulletproofmeteor.com/basics/?lesson=defer-the-execution&step=4