If you think you'll ever need customer support, don't use MailChimp. I feel like I'm talking to a wall when I contact their support team and often have to repeat myself. They don't have phone support. Sometimes the wait for chat support can be up to 15 minutes long. Any time I have an issue, I have to expect I will at least be on chat support for a half hour to 45 minutes going back and forth with them. I also use HubSpot and this is not the case with HubSpot. HubSpot's support is fast and knowledgeable. I'm feeling very frustrated using MailChimp and am trying to get my company to get rid of it.
