When speaking with clients it can be tempting to respond with "smileys" or jokes, but there are a few guidelines you should follow to remain professional and respected:
1) Make it easy to read and understand your message Use complete sentences, not random unfinished thoughts. Do not use slang, specific terms or acronyms. Make your message brief and to the point. Concentrate on the subject matter.
2) Use proper grammar, spelling and punctuation Use a proper sentence structure in your email messages. Spell the name of the recipient correctly. Do not type your message in ALL CAPITAL LETTERS - this is considered shouting according to email etiquette rules. Do not type your email in all small case either - this gives the perception of a lack of education. Avoid using informal words.
3) Use a neutral tone of communication Refrain from becoming informal. Avoid using multiple instances of an exclamation mark (!!!) or a question mark (???). Do not use emoticons in business emails they look unprofessional. Don't use sarcasm or irony; they can be misinterpreted easily.
4) Be thoughtful and polite Start every email with a greeting. Make sure to use an appropriate salutation. Dear or Hello is acceptable. Hey/Hiya are considered too informal. Never forget to include a closing phrase at the end of the message, e.g. Regards, or Thank you. Don't hesitate to thank your recipient in case they were of help. Do not forward email messages without your personal comment or a short personal note; otherwise this may sound impolite.
5) Take advantage of signatures and auto-replies Use an email signature with your contact details. This will give your recipient more options to continue communication. Use the auto-reply feature when on vacation.
6) Check it twice before you send Check your email before sending to see if you wanted to send an attachment but forgot to include it. Make sure the Subject field in not empty. The subject line should reflect the main idea of the message. Spell-check your message before sending: a message with typos can be treated as unserious or even be ignored. Before clicking Send, reread your email to make sure it is not emotionally charged or impolite. Respond to emails within 24 hours of a business day
7) Manage your emails efficiently and respond within 24 hours of a business day