What's better, original date of draft or latest date of draft in email?

I’d expect it to have the timestamp of the last save event. I.e. latest.

^ Yup.

If you use a word processor like Word, you can find both dates in the metadata.

Is it when the letter was started or when it was updated that is more important info, in general, and a document like Word wasn’t used.
Thanks @2davidc8 for the tip.

Which one is more important might be up to you.
Personally I would find latest update most useful on documents, but I can see how the initial creation date could be more useful for some people/purposes.