According to science you should never put smiley faces in work emails

:( :( :(

There's a fine line between friends and co-workers and often that line gets blurred.

Should you invite your work colleague to your birthday party? Is it appropriate to tell your co-worker about your tumultuous love life? And, how many glasses of wine is it socially acceptable to drink in front of your boss?

There are so many questions we need answering to help us locate the professional line, the biggest being work email etiquette - and more specifically the use of smiley faces.

Smiley faces are a great way to punctuate texts and messages, whether it's for softening blows, relieving awkward moments or just making your message seem warmer. However, it turns out there's a limit, with using them in work emails actually having a negative impact.

According to a new study published in the journal Social Psychological and Personality Science, using smiley faces in work emails has a huge effect on how you're perceived, particularly in terms of age, gender and competence.

The study, conducted by researchers from Ben-Gurion University in Israel, involved three experiments, featuring 549 people over 29 different countries, evaluating the difference in people's perceptions when receiving an email with or without a smiley face.

While the study showed a general assumption that the people who sent smiley faces tended to be young and female, the most interesting point to come out of the experiment was the effect it had on perceived competence.

'Our findings provide first-time evidence that, contrary to actual smiles, smileys only marginally increased perceptions of warmth and actually decrease perceptions of competence,' explained Ella Glikson, an author or the study, in a press release. 'In formal business emails, a smiley is not a smile.'

Her advice? 'In initial interactions, it is better to avoid using smileys, regardless of age or gender.'

Well that's certainly given us something to think about :)