I just sent my first regular campaign email. (By mistake, because it wasn't finished and wasn't intended to go out until Tuesday, but that's neither here nor there.)
This email has a bounce rate of 15.1%. This is concerning, since I've never had nearly that high of bounce rate before with MailChimp, and this was my first use of a regular email.
Hard bounces 0 / 0%
Soft bounces 4 / 2.162%
Internal bounces 181 / 97.838%
What is a soft bounce versus and internal bounce?