Nobody really knows all the unwritten rules to sending colleagues emails, hence why so many people still manage to get into trouble thanks to an email gone awry. Therefore, it is sensible for someone to write the rules down, just in case the email you're about to send happens to break the unwritten rules.
1. Never criticise a colleague
Truthfully, if you're going to criticise someone at work, it is perhaps best done outside of work and with a group of friends who don't work in the same place you do. If you do have to criticise, make sure it's about their work, it's constructive and carried out in a professional manner, not a bitchy email about personality flaws.
2. Bcc is for distribution lists …
… Not trying to hide away the other people you've sent your email to. Should you wish to say something and let others know, be polite and copy them into the email without the bcc stuff.
3. Your work email – it's for work
Remember: keep your personal and work life separate. Your work email is not for your friends and family to send spam to, it's not for mailing lists and it's certainly not suitable for use on dating websites. Use a separate email address for such things.
4. Keep your signature simple
No jokes, no pictures and no quotes. A simple name and contact details ought to suffice for most purposes.
5. Shorter is sweeter
Strange as it may seem, your colleagues may lead busy lives and do not wish to feel accosted by chunks of intimidating text. One to two paragraphs should be enough for most emails, and can keep things tight and to-the-point. This is especially important to remember for crucial emails, where large bits of text can detract from the purpose of your email. Extra-long pieces of writing are usually best sent as attachments. Use numbers/bullet points wherever possible.
6. Irony and sarcasm are hard to read online
Should you write something with a hint of irony or sarcasm in an email, most people won't pick up on it. People tend to read things literally online or in emails, so it's perhaps best to leave such literary devices to creative works or personal emails where there's plenty of context.
7. Use legible fonts
Why do so many word processing programmes have so many unreadable fonts that no one uses? No one knows, but it's best not to risk experimenting with the mistral and brush scripts. Arial and Times New Roman are fine.
8. 'Reply all' with caution
Many a time someone been caught doing something naughty, offensive or been misunderstood thanks to the wrong click of a button. In case of doubt, do not reply.
9. Don't pester
So, you haven't had a response to that all-important email you sent a few days ago? Yes, it's fair to send a follow-up email once or twice spaced out over a week or two but that first follow-up email should be sent no less than two days later. Any more than three in one month, however, and you could be seen as no different from spam to someone whose time might be precious and spread thinly.
There's nothing worse than an email which says “this looks great” with a load of other emails saying “I agree”, “me too”, “me too”, ad infinitum. As such, it is contentless drivel and usually adds nothing to a discussion. Write something worth reading, or don't write anything at all.