does not return acknowledgment of receipt
That really depends on the recipient, their mail server and the email application they are using.
Some apps and webmail do not display the read receipt request, so the recipient will never know you asked for one. And even if they do, the recipient has to acknowledge your request. If they just ignore it, you won’t get the receipt.
Delivery receipts are obsolete, and most servers don’t send them. You can assume your message has been delivered unless your server sends you a message to say it can’t be delivered.
domingoo 18 diciembre 2022 :: 0911hrs (UTC 0000)
Will only work if NOT disabled on recipient email client.
¡Buena suerte!
¡Saludos desde Banjul la soleada en Gambia!
skybat
Hablo español, luego portugués e inglés, con conocimiento de varios otros idiomas.