I have list of subscribers from my old blog. Now I want to resubscribe users to my new blog. But when I upload list to MailChimp I've been banned. From support, I know that my list isn't clean, like lots of dead mails in it. How I can improve list quality to finally start sending mailings?
You may use email validation service, like mailcheck it's not unique service, but comparing to others they do contact enrichment. Like showing you Surname of yours prospect. It also could be helpful.