Create name abreviations in Address Book

[Old Red One]

When clicking names after opening the To box, an abreviated (three letter)
entry will bring up the needed name. E.G. for someone whose address is,
say, luvable@such&such.net, the three etters 'luv' will cause the address to
fill in.
How is this determined? And is it possible to create a different three
letter entry to generate a fill in?

 

[Roady [MVP]]

It's being read from a cache of names you've recently used. There is no
"three letter abbreviation" feature; your typed three letters matched with
only a single entry in you cache so that is why it is the only address
offered.