List Janitor is very easy to use and great software to clean your mailing lists. It removes duplicate and invalid emails and verifies email deliverability. You have also the choice to remove role IDs (such as admin, sales, support etc.). Just upload your list (text or csv format) and with 3 clicks you get a cleaned list while keeping removed emails in separate list.
[WordPress Plugin] Mail It is the simplest and cheapest solution on the market right now to send emails to your subscribers directly from inside your WordPress blog without paying fees anymore for your ESP/Autoresponder and/or SMTP relay services. Send unlimited (broadcast or autoresponder) emails to an unlimited number of subscribers at any time and as often as you want without any restrictions that major ESPs seem to have. Hence, a great plugin and must have tool for any serious Email Marketer. Even if you’re only going to use it as backup opportunity in case your Autoresponder can’t be reached or doesn’t work temporarily (or even worse if they “closed your account” without warning).