Netsafe chief executive Martin Cocker said there could be some degree of bias in the results, in that respondents might not recognise that they had, in fact, sent something harmful.
Those saying they did so "as a joke" likely had later realised or been told that something they sent was "incredibly offensive or harmful" to others.
"I think that people are probably fully aware that racial slurs, sexist, homophobic, ableist comments are harmful, but unfortunately see or consider those sort of comments to be sent in jest or humour."
The other main reasons people sent harmful digital communications were "to influence behaviour or thoughts" (14 per cent), "to scare" (8 per cent) and "to embarrass" (6 per cent).
Six per cent of respondents admitted to saying offensive things about someone else, and 3 per cent tried to embarrass another person, attempted to exclude someone from a friendship group, or made a sexual advance they were not sure was welcome.
Some examples of harmful communications people had given to Netsafe included the sharing of traumatic sexual experiences online, people "outing" someone while believing they were acting in the public interest, and blackmail for intimate images with threats to share the ones the perpetrator already had.
Other examples were encouraging people to "spill the tea" by sharing gossip and rumours online, threatening, abusing or harassing someone due to political differences, and abusing ex-partners.
The process Netsafe goes through when dealing with people who send harmful communications allowed them to factor in whether people were deliberately causing harm, or whether they were accidentally sending something without realising the harm it could cause.
They were able to work with those people and educate them, while prosecuting or taking action against those who were more deliberate with their messages.
"Netsafe can help people who have been the recipient of deliberate abuse and also assist people who didn't intend to hurt others," Cocker said.
"It is important to see deliberate offenders prosecuted, but also to provide ways people can reverse harm that they may have accidentally caused."
The findings also showed the vast majority of people who sent harmful messages in the past year also received them.
Texting or messaging from a cellphone was the most common way of sending harmful communications (39 per cent), followed by social media posts (34 per cent) and emails (20 per cent). The least common method of sending harmful messages was through online games (4 per cent).
Much of the research confirmed theories Netsafe already had, including that the largest proportion of harmful messaging was sent between people who already knew each other. Only 13 per cent said they sent harmful digital communications to a stranger.
Nearly a third were friends of the recipient, and a fifth were family members.
Netsafe's results are being released to coincide with Safer Internet Day, a global awareness campaign involving more than 170 countries, to promote a more positive time online.
Last financial year, Netsafe received 22,705 reports and nearly 3400 fell under the Harmful Digital Communications Act.
Netsafe is available seven days a week to provide free, confidential and non-judgemental
support to those experiencing online harm – or for people who have been sending material likely to upset or affect others and who are looking to make amends.
What Netsafe counts as harmful communications
Netsafe specifically asked people about messages they sent or shared that:
• Physically threatened someone
• Attempted to get someone excluded from a friendship group
• Tried to embarrass someone online
• Said offensive things about someone (e.g. the way they look, how they behave, or what
they believe in)
• Included violent or sexual content
• Was a false statement about someone's personal or professional life
• Was a sexual advance toward someone that may not have been wanted (e.g.
messages about sex, naked selfie, images or video live stream)
• Involved regularly monitoring someone's online activity in order to influence their
behaviour or thoughts
• Shared intimate images or recordings of someone without their permission
• Encouraged other people to send hurtful messages to someone else.
