A student of mine once asked about this email opening sentence. She didn’t know how an email, as an inanimate object, would literally FIND the recipient. Yesterday, I came across the same question again on Zhihu, a popular Chinese Q&A site paralleled by Quora.
It should be noted that the word “well” here is not an adverb but an adjective, which describes a state of good physical health or satisfaction.
— How is your sister?
— She’s very well. Thank you.
Also, the verb “to find” does not mean “to obtain”. Instead, it means “to experience” or “to look at”.
My sister quit the job because she found it much too demanding. (= She regarded the job as extremely onerous.)
Therefore, such parlance as “this email finds you well” actually employs the tool of personification: when this email gets to you, I hope that it (on my own behalf) witnesses the fact that you are sound in both body and mind.
In English, “you” can be one person or a group of people. In light of this, 「展信佳」(to a singular recipient) and「闊府康泰」(to an extended family, usually of high social standing) might be qualified Chinese equivalents.
With the above being said, I won’t expect anyone to use it, for it sounds a bit old-fashioned and hackneyed to me. In this Digital and Information Age, we’re suffering infobesity to a great extent. When trying to reach someone, always bear in mind that brevity is a virtue. Instead of being annoyingly wordy, simply use I hope you’re well, which should sound much better.