Whenever you say cost-effective you must understand what are the costs that you are incurring. There are primarily the following types of cost a company incurs. First one that comes to our mind is variable cost. Variable costs will vary in direct proportion to changes in the level of an activity. Second is Fixed Costs. The opposite of variable costs are fixed costs. Fixed costs do not fluctuate with changes in the level of activity. Economists speak of the concept of economies of scale. This means that certain efficiencies are achieved as production levels rise. Keeping all these costs in mind you can any mass emailer and that would be effective for instance Sendinblue, sendgrid or elastic mail.
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