Ah, email, the timesaving tool that swept in and blasted letter-writing out of the water with its exceptional speed and efficiency. Or, at least, that’s how it felt back in the 90s.

The trouble with email is that it arrived in an era of formal communication that the modern office has all-but forgot.

Letters, especially formal letters, are governed by a clear set of rules and codes. Email, which was built as a virtual version of letters, was more of a communication grey area, spawning a hazy etiquette system all of its own.

The advent of instant messaging muddied the waters even more, with habits seeping across into email that horrified some but were warmly welcomed by others.

Nowadays, emails can feel like a minefield. Who hasn’t wasted an hour crafting a simple message because they’re worried their tone will misfire and cause offence?

Here are the top four email etiquette nightmares:

1. You lost me at hello

The very first word of your email is often the most fraught. Nowadays, most people start with "hi" but there’s always an exception who deems anything but "dear" impertinent. And if that person is a new/potential client, you’ve made a bad first impression already.

What’s more, you then have to figure out at what point in the email exchange you can launch straight into answering the question with a simple "hey" or no salutation at all. If neither of you are willing to risk it, you can go on writing bulky formal-sounding emails (and wasting precious time) for weeks!

2. Re: Re: RE: fwd: Re: Changing the subject

Email subject lines can be a total pain when you have to trawl back through your inbox for a key piece of information.

For some reason, changing someone else’s subject line feels rude, and no one wants to be the first to do it.

The conversation might have moved on from the original point days ago, but everyone copied in feels that they have to keep the subject line (and the entire email chain to date) as a reference point for all their replies.

Even though this means sending all the same information to each other, over and over again, with just a single new line tacked on the top. How inefficient.

3. Brusqueness

Because email falls into that tricky place between formal letters, social media and instant messaging, it’s really easy to misjudge the tone and sound as if you’re being rude or rushed.

Sending a text that simply confirms the answer to a question or warns someone that you’ll be late can be a few words long without seeming blunt, but write the same thing in an email and your recipient might well take it as an affront.

4. Over-friendly sign-offs

There comes a time in everyone’s life when they find themselves staring at their screen wondering how one tiny letter can cause such panic. Such is the power of the unexpected "x".

Adding a kiss to the end of a text to a new friend is awkward enough. Are you being forward? Is it appropriate? Will they find this weird? Throw a work relationship into the mix and signing off becomes a high-stress situation.

So what do you do when a client, colleague or contact sends you an email with an "x" on the end? Ignoring it is probably the safest course, but there’s always the risk that you’ll cool off a (professional) relationship you’ve been fostering for a while. It’s enough to make you want to ditch the laptop and train a carrier pigeon.

Avoid these four email etiquette faux pas, and you'll be just fine. Or check out the further resource on information about how to write a professional email.