I get people emailing me math questions every once in awhile. I never answer them (I strongly prefer to answer math questions in a public forum like Quora or StackExchange), but some of them are at least tempting. I am actively turned off by any attempt on their part to use flattery, and those are never tempting. It always sounds fake to me. (Also, some of them call me a professor on accident and that's annoying too.)