On my Apple OS X system, the Microsoft Outlook 2016 and also Apple Mail clients display the name next to the FROM address for incoming emails. I notice that it's not always the same name I have listed for that address in the Addressbook, and even more weirdly, I've seen it listed in my Inbox multiple different ways (e.g., with different capitalization for example) for emails coming from exactly the same email account (I've seen examples especially coming from specific Gmail and Comcast addresses, with emails arriving within hours of each other, sitting in my Inbox with the same from addresses but differently displayed from names). Can someone explain how this works - where do email clients get the string they want to display as the name?
The name is displayed in the way it is stored in the sender's address book, or how the sender has chosen to format it.
If an e-mail is address simply to
email@example.com then e-mail clients will normally display the entry in the local address book. However, the sender can add a name to the e-mail address, such as
"The person I want" <firstname.lastname@example.org> and this name will be displayed in the client.
The addressee can be entered from the address book, or typed manually. This is quite useful, especially if several people share an address, eg
"husband" <email@example.com> or
Searches for e-mails from or to specific addresses will normally take into account both the name and the address.
I don't normally use AppleMail as a client, but this can be done on any client, though the precise syntax of the composite address could vary.