This makes sense if they are proper recruiters. I usually just ignore those unless I'm looking for work. But the worst kind are the recruiters based in India -

This makes sense if they are proper recruiters. I usually just ignore those unless I'm looking for work. But the worst kind are the recruiters based in India - they keep sending irrelevant emails for jobs in the US where I don't even live, and no matter how many times I flag them as spam in Gmail they keep going through. I think they found a loophole to go around Gmail spam filter, so the only way is to manually add them to a filter.