The API call to the endpoint https://api.cc.email/v3/contacts/sign_up_form returns "Email address is invalid" for most calls. Here are five example email addresses all rejected as "invalid" (both by my production application and also using the "test" feature of the API docs): naomi.wongwui@diamondresorts.com tylerader@yahoo.com jtheodore@siebert.com PAMELATJOHNSONPHR@GMAIL.COM bapslansdale@gmail.com ... View more