Hi, Alexander! Recently you wrote in a message to Alan Ianson:
If this was you, you're all set!
I just thought that the rule should follow from the rule
"I was, you were, he was"...
Ah. While the use of "if" does add a layer of complexity here, the issue appears to be more about pattern recognition.
When you knock on somebody's door & they ask "Who's there?" you can answer (formally) "It is I" or (informally) "It's me" as long as they know you well enough to recognize your voice. Although Yahoo can't hear your voice, it can use other means to let you know what's going on in case somebody is trying to impersonate you. If all is well, no reply is necessary.
When I drop something in the kitchen & Dallas... who is in the next room... asks "Was that you?" he's doing much the same thing. He knows from my response whether or not to grab his cell phone & prepare to call 911. :-))
Yahoo is using the sort of informal English native speakers tend to use with family & friends when Miss Stickler can't hear them. Another example may be seen &/or heard in one of our favourite short stories, THE DAY DAD MADE TOAST. When Dad asks Mom "Where are the big blue plates?" she replies "In the dishwasher." Robin Williams does quite a nice job with it on YouTube.... :-)
In its entirety, Yahoo's message is a two-part question: "Somebody tried to gain access to your account using [blah blah]... was that you?" IMHO the response Yahoo anticipates is "Yes, it was me" or "No, it wasn't me". :-Q
--- timEd/386 1.10.y2k+
* Origin: Wits' End, Vancouver CANADA (1:153/716)