Anytime you do something that would be considered an extreme or ironic failure when sending any type of mail (i.e. email or letters). This can be augmented with the words epic and absolute.
just straight up fucking failing with anything involving mail or internet
When you are sending extremely private or revealing information via email and accidentally clicking the "reply all" button. then epically fail resulting in a mailure
A failure to convey an idea or emotion in an email communication, due to the impersonal nature of text.
Jan didn't understand a word of where I was coming from in that email.. it was a complete mailure.