MailChimp just posted how they sent 1.5 billion emails through their system on Black Friday. It was followed on Cyber Monday with 1.4 billion emails. You can read more about here:

A New MailChimp Record: 1.5 Billion Emails on Black Friday

Those are pretty impressive numbers!

I used to work as Technical Lead of Deliverability at an ESP. For the years I worked there I never saw numbers in a single day reached over 1 billion. If there was ever a time of the year to reach over 1 billion it would be Black Friday or Cyber Monday. Those were always the biggest days in regards of volume leaving our system.

Thinking of this number it sounds like MailChimp has a stable system to sufficiently send 1.5 billion emails in a single day.  I am really curious what their setup is and how they were able to handle it so well. Or maybe there were some hiccups but nothing major that caused delays. Regardless, this is really impressive and it’s nice to see a blog post about their numbers that entire week.