Some 51 per cent of companies send large volumes of emails that users have not explicitly consented to receive, according to a research report by independent agency Spam Ratings.

In a separate study of 1,000 consumers by research company Toluna, 60 per cent feel respected brands are trying to trick them into receiving email marketing.

Some 58 per cent worry about unsolicited emails on a daily basis, with 67 per cent of respondents saying they are annoyed by email spam from recognised brands.

Co-founder of Spam Ratings Andy Yates says: ‘The research shows big brands are shooting themselves in the foot by sending huge numbers of unwanted emails and weary customers are now at the end of their tether. It is clear that consumers want to be able to choose whether they receive emails – because of this they want businesses to act responsibly.’