A manager had been emailing me monthly requests to update some time-tracking excel sheet, but his emails looked like the kind of automated spam you get from every other service reminding you to do something or other so I ignored them. And I was tracking my time following a different process (you had to do both unbeknownst to me) so I assumed it was just an automatic reminder and I was good.
Anyway 6 months into the job he called me on the phone and gave me the dressing down of a lifetime about responsibility and answering your emails and so forth. Very unpleasant experience all around.