without limitation , you agree not to send , create , or reply to so called `` mailbombs '' -lrb- i.e. , sending copies of a single message to many users , or sending large or multiple files or messages to a single user with malicious intent -rrb- or engage in `` spamming '' -lrb- i.e. , sending unsolicited messages for business or other purposes -rrb- in addition , you agree not to send `` bulk messaging '' -lrb- i.e. sending messages for business or other commercial purposes -rrb- without written permission by viber , or undertake any other activity which may adversely affect the operation or enjoyment of this service by any other person , including placing malware on the service .