Changing Email Service Provider in practice

The project starts with a decision to change ESPs, and there needs to be a solid business reason to change. Your current ESP needs to be limiting your core business in a severe enough manner so that even adding other tools won’t help you. So, how to change ESP? One of the reasons may be getting access to better reporting. Depending on the reputation of your old ESP vs. your new ESP, you may lose subscribers as well. In one ESP transition where my company moved from a B-level ESP to an A-level ESP. So even before you would ask "How to change ESP" you have to ask yourself "Do i need to change it?"