On it's surface the email, obviously, looks like the rant of a textbook paranoid schizophrenic. There are a few simple cross checks to determine if it needs further investigation. Did the sender have a know and more or less sensible relationship with the recipient prior to this email (i.e. were the two individuals associates in any normal sort of way.) How about afterwards, did they become or continue to be associated with each other (work, family, socially) ? If the answer to either question is yes, then the letter should be taken very seriously indeed. What I mean by "seriously" is that if the guy is NOT simply a garden variety nutjob then the letter reveals imbedded code-like phrases and MK-Ultra references which suggest that the program was not as wacko/failed as it was assumed to be back in the day, and has both expanded and is more practically useful than we thought at that time. If ( and ONLY ONLY ONLY if ) that is the case, then the email is an extremely rare and valuable lead into things dark and dangerous enough to warrant the most intense focused investigation. Ever. If MK Ultra actually WORKED , if it matured and expanded into anything with practical application ( and was not simply the fever dream money-funnel and playground a small cadre of depraved sexual psychopaths) then I would say that rooting it out would take precedence over absolutely every other thing you might possibly have on your plate. Having said that, however, be forewarned that you tread along the fragile rim of insanity when looking into such stuff. Cold and uncompromising scientific method and hard evidence are your only lifeline.