Typically You need an email service provider to do the bulk send and you need to comply with CAN SPAM laws. Most of this is around giving people the opportunity opt out of future emails.
Have you tried creating a distribution group? It does sound like you need to do some data cleanup though. Is the file too big to manipulate in excel?
https://support.office.com/en-us/article/Create-a-contact-group-from-a-list-of-contacts-in-Excel-4d7ab35c-0bdf-4dc2-8279-477c1a79ab72