They have about 10,000 subscribers currently but they haven't sent any email in over a year. They had a ton of internal challenges which I won't get into which have set them back and they're about a decade behind in their technology anyway.
I have experience with MailChimp and Constant Contact, but that has typically been with smaller lists, nothing over 3,000 members. Maybe they've already outgrown services like MC and CC? Maybe that's a good fit?
I'm also looking at using CiviCRM and WordPress.... it looks like CiviCRM has some kind of email marketing software built-in - will that work?