Apple's Mail doesn't just autocomplete addresses typed into the "To" field, it also recognises partial names and even initials.
If you have many friends named "Alexander," it can be a pain typing the whole first name just to get to the differentiator -- the last name. It turns out that not only could you type alex a or alex b , but you can type a a and a b to find the first Address book entry that starts with those initials.
I haven't yet confirmed if previous versions of Mail do this, but I suspect it's a Tiger thing, because it seems to go on to find all contacts who have those characters in the respective names (i.e. typing n m will find all contacts with an "n" in the first name and "m" in the second).
•
[6,427 views]

