No emails have a particularly high open rate, for a number of reasons: even transactional emails such as invoices often struggle to 50%. The type of email that appears to get the highest open rate turns out to be the very first email you send someone by request – the ‘welcome’ email in most cases.
Now, depending on the marketing strategies you employ, that first email could be ‘thanks for requesting our catalogue’, ‘thanks for signing up to our mailing list’, or even ‘thanks for your order’. But whatever it is, that email is more likely to be read than any other, so it’s a big opportunity to establish relations. You may have a series of emails or sales initiatives scheduled to follow that first email – perhaps automated – but that email should be the first one in the series, not a throwaway document. Of course it should say thank you. But don’t waste the opportunity to offer more. You must have something!