man mail says:
mail [-iInv] [-s subject] [-c list] [-b list] to-addr [...]
          [-sendmail-options [...]]

however when i try to place some sendmail options as described in man/help/info
files with something like:
mail -s "test" thresh@domain.tld -f root@domain.tld < file
it says:
mail: Cannot give -f and people to send to.

It looks like sendmail options should be placed after doubledash, smth like this:
mail -s "test" thresh@domain.tld -- -f root@domain.tld < file

And, yes, finally it works fine.