Will this library work with Windows Phone 7 & 8, or do we need the Windows8 Metro version?
Mail.dll email component requires full .NET framework or Mono.
MailForWindowsStore.dll works with .NET 4.5 for Windows Store Applications and Metro UI: https://www.limilabs.com/mail-for-windows-store
MailForWindowsPhone.dll works with .NET 4.5 for Windows Phone 8.0 and 8.1: https://www.limilabs.com/mail-for-windows-phone