Hi @StR, do you speak European or Latin American Spanish? Have you checked Outlook Es-La / Es-Eu to see the differences?
Which Latin American Spanish? Latin American - Mexico City or Latin American - BsAs?
"The difference between the Latin American Spanish spoken in Mexico City and Latin American Spanish in Buenos Aires can be significant. It is probably as great as between Buenos Aires and Madrid or between Mexico City and Madrid." Source:
http://www.trustedtranslations.com/spanish-language/translation/latin-american-spanish.asp 
Mil disculpas que no hablo Español.
But I do not know any version of Spanish in which "recibo" would mean "read".
So, whoever translated "read receipt" as "Acuse de recibo" does not understand what English "read receipt" is.
"
Acuse de recibo" would
not mean "acknowledgment of
reading",
but rather "acknowledgment of
receiving". (The meaning is very close to "Acuse de entraga"="acknowledgment of delivery")
Now, the question is: What is correct (for "read receipt", i.e. acknowledgment of reading)?
So far, there are two versions on the table.
"Confirmaciones de lectura" (as used by Google, MS, WhatsApp, ..) and
"Acuse de leido" as suggested by Julio.
From what I understand, the biggest objection by Julio is about the word "lectura".
Since his claim is about the numbers (more people speak es-la [Latin America] than es-es [Spain]), let's do some numbers.
Google search for "acuse de leido" (use the quotation marks to search for the entire phrase!) gives "about
1420 results".
https://goo.gl/YptCYfThe same for "acuse de lectura" gives "about
62,200 results".
https://goo.gl/0m2syB "Confirmación de lectura" gets about
166,000 results.
https://goo.gl/OqqwH8(For completeness: "confirmación de leido" gets just 1,880 results)
And one of the first links when you search for "acuse de lectura" (2nd for me, but it can be different for others), is to a website in Argentina, "La Nacion" (a major daily newspaper in Argentina.)
http://www.lanacion.com.ar/1480420-como-chatear-desde-el-celular-y-saber-que-el-otro-leyo-el-mensajeEs lógico que la mayor parte de la gente tomara ese signo como un acuse de lectura (que no es) y no de recibo (que es lo que informa)... (Crude translation: It is logical that most people take that sign as an acknowledgment of reading (which is not) and not receipt (which is what informs)...)
And, while we are reading that article, further down, there is this sentence:
Pero no ofrece la muy conveniente confirmación de lectura. (The article actually uses the word
leido to describe that the message is read, just not in combination with "acuse" or "confirmación".)
So, a major Latin American newspaper uses both "
acuse de lectura" an "
confirmación de lectura".
And Google shows that "de lectura" is winning by
several orders of magnitude!
I rest my case.
PS. It's noteworthy that "
acuse de recibo" (479,000) wins over "confirmación de recibo" (122,000) in Google by a factor of ~4, and less than by a factor of ~1.5-1.6 over both "acuse de entrega" (295,000) and "confirmacion de entrega" (322,000).
