Why does " Received: from smtpclient.apple " show when apple was not the email host?

[Hoboken91]

I received an email from someone who used an @comcast email address.
I looked at the source. (what I mean here is all of the technical information surrounding the email.)
here is one line from there
Received: from smtpclient.apple ([xx.xx.xxx.xxx])
(instead of the numbers for the IP address, I put the letter x.)

Because I know the person a little, I know that they could have sent the email from an iPhone.

I am just confused and trying to understand what role Apple has in the email transmission.

I am not using any Apple products so it shouldn't be caused on my end.

 

[Bigwaff]

It’s one of the message receiving servers in the chain of servers receiving the message. In email message raw headers, receiving servers are listed from bottom to top, server by server.

 

[Hoboken91]

It’s one of the message receiving servers in the chain of servers receiving the message. In email message raw headers, receiving servers are listed from bottom to top, server by server.

over my head.
So when the user is using the Mail app, Apple servers get involved in receiving the emails (maybe sending, too)? Logically, I don't understand why that is necessary. How standard is this across mail clients?

 

[Bigwaff]

How standard is this across mail clients?

It’s not email clients. It’s how email servers, the backend servers, work. Email messages are relayed from server to server until they reach destination server where the message is eventually picked up by the client(s).

I don't understand why that is necessary.

If only there was a service available where you can find out practically any information of interest. Wealth of information available at your fingertips. If only.

 

[Hoboken91]

If only there was a service available where you can find out practically any information of interest. Wealth of information available at your fingertips. If only.

I have tried a couple of search engines and they don't really shed light/ add to what you are saying. (I think you are saying that Apple is running mail servers of its own that serve to just transmit emails across the internet.)

I might add that the sender of the email is not using the "hide my email" feature.

 

[chown33]

The protocol used by Apple's mail servers (and countless others on the internet) is SMTP. You can read more here:

Simple Mail Transfer Protocol - Wikipedia

en.wikipedia.org

You could also ask an AI to summarize that article for you, if you don't want all the details.

Here's another article on the basics of SMTP.

https://www.cloudflare.com/learning/email-security/what-is-smtp/

You should be able to find more with search terms like: simple smtp summary

One key point of SMTPis that mail delivery from sender to recipient may involve multiple servers. That is, it isn't necessarily a direct single-hop delivery. Instead, SMTP servers will relay messages on a route that goes from server to server until it reaches the desired final destination. An analogy is a shipping network for goods, that may involve ships, trains, aircraft, long-haul trucks, delivery trucks, warehouses, etc.

As each server relays a message, it adds its own name to the top of one of the headers in the message. This gives a "trace-back" of how the message moved through the relaying servers. This info can be useful in diagnosing failures.

 

[NoBoMac]

Normal. Person used an Apple device's Mail app.

For example, here's the entry for an email I sent out from my Mac using Apple's Mail via my main Gmail account.

Received: from smtpclient.apple ([xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx])
        by smtp.gmail.com with ESMTPSA id

 

[chown33]

Here's another detail: sending email can happen through a different server than the sender's destination address signifies. For example, someone with a comcast.com email address can send emails via an Apple SMTP server. Both linked articles mention IMAP and POP servers, which are typical for email retrieval (reading one's received emails).