Email marketing is the most profitable marketing channel, garnering an ROI of $42 for every $1 spent. However, if you try to start a mass marketing email campaign through your Gmail or Outlook account, you’re going to be hampered by send limits and you could even end up having your personal email or your entire organization’s domain blacklisted (more on that in a moment).

So how do firms manage to conduct email marketing campaigns that send hundreds or thousands of emails and still hang on to their online reputation? Email marketing services or email service providers (ESPs) are third-party services that handle mass marketing email sends. ESPs take a number of measures to ensure they remain whitelisted and retain agreements with internet service providers (ISPs) that allow them to send emails in bulk. 

You might be asking yourself, “Why do I need to pay extra to send emails when that’s what I do all day, every day? Why not just send each marketing email individually from my individual email address?”