I usually filter immediately out. ( sorry, i don't do java or unity - yes i might have worked on them 6 months 10 years ago, but definitely i don't fit the java senior or game developer position you are offering - or very interesting, but not considering relocation. )
those that i can't - because they could actually work, it's harder. still reply i am not considering to change because iI just started a new project / role and want to finish it ( and no, i dont'want to just have a talk to update your database) and suggest to catch up in 6 /12 months.
normally i reply to all requests altogether once every week/two weeks. ( so not really immediately)
i try to always be polite, and when i am pissed off... i write these posts here on dev! ;-)
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