Hope this email finds you well./ Hope this email finds you in good health.
谨以此邮件向您致以问候.
原文为英文正式邮件的套词,出处无法考证,大致意思说法不一,但可按中文习惯进行翻译.
另附某国外网友的解释（解释不一,没有定论）：
It is to confirm from the receiver of the email that they are doing fine and everything is going fine with them personally and professionally they will respond to you e-mail quickly and not make the e-mailer wait for a long time.