[emeritus]

Before I retired I worked for a legal firm, and we certainly used fax as well as email and post for important communications where time was of the essence. Producing a fax "sent" receipt was certainly accepted by legal authorities as demonstrating that a document had been received, which could be vital in showing that absolute deadlines had been met if the recipient had mislaid the fax at their end. I well remember doing a stint of bank holiday cover when the office network went down, taking out all the phones, copiers and networked fax machines, and having to give urgent instructions to a foreign client on the one fax machine that had its own dedicated phone line that had been provided for just such an emergency.

I guess secure email ought to be reliable as long as you have a reliable internet connection: ordinary email certainly is not. My wife sends out scores of emails in connection with organizing rotas, and a proportion of them never get delivered. We have even experienced several examples of emails sent between our BT email mailboxes not arriving, despite no errors having been noted in the sender's outbox. Only last week a confirmation of a dentist's appointment sent by the dentist on Wednesday afternoon wasn't delivered until 4.30 AM on Saturday.