Is my yahoo email address automatically a yahoo IM?

I sent a new friend an email and he said he just added me in his yahoo IM. Does it mean that I can just use his email address as his yahoo IM id and he will be seeing me joining? Yes it is sort of sensitive so I don't want to ask him. :-) Thank you for your answers.

Is my yahoo email address automatically a yahoo IM?
If his Yahoo!ID is the same as his email address then Yes.
Reply:yes it is

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