The print equipment and cross-media specialist has produced a white paper entitled Why some customers are just not that into you – a survey conducted with more than 5,000 consumers across the UK, France, Germany and the US.

It looks into the success rate of a number of different communications, including email and direct mail.

Pitney Bowes UK managing director Patrick Jelly said that just 24% of emails, when sent as a solo communication, will be opened. This is down from 30% in 2010.

The survey also found that 53% of respondents consider monthly emails to be intrusive, while just 23% said the same message by post would annoy them.

Jelly said: "It is not about using one medium or another; it is about getting the right message across in a timely fashion.

"Pitney Bowes has also looked into a number of techniques when using mail. Personalised mail is more likely to be opened, while if you use colour on the front of an envelope you are 72% more likely to have it open. So if you use colour and personalise the mail, you are really in business."

The survey also includes a list of "seven deadly sins", which should be adhered to when dealing with customers via email.

Failing to provide an opt-out clause (89%) was the chief bugbear, while sending customers advertising emails every week (88%) was second.