capitalized MAIL

in the US, a woman was fired because of sending capitalized e-mail. the article says that the woman sent a e-mail to hey co-worker, and the co-worker felt disharmony. that why she was fired the company. and then she got angry, she sued the company. in the end, she won the company, and she got money for compensation.
from what the article said, i do not know why the company dismissed her. only a e-mail is the reason? it does not make any sense. she might think all capitalized e-mail is easy to read, or all capitalized e-mail is easy to write. whatever she thought, the e-mail did not come to the reason that she is fired.
however, she should have thought how the co-worker feel when they got the e-mail. i think she did not think about what they feel. that why she sent like that e-mail.
in japan, we have a lot of limit in the company or our life. we have much manner, and we should keep behave good to old people. so i think maybe this case is going to happen in japan. we should learn the manner.