I do not recommend the expression of annoyance, rejection, or anger via email or texting. It may be the easy way out, but it doesn't solve the conflict actually, it can escalate it to a point of no return. And no one wants that in a working place. When you are about to hit the send button on that angry email or text--stop:

Emotions are usually best expressed when the other person has the opportunity to read your body language and facial micro expressions--whether they are of admiration or annoyance. Emotions are also best expressed when the other person has an equal opportunity to respond face-to-face, so you can talk things through.

Expressing feelings together in a shared situation can help reduce misunderstandings, misinterpretations, and the escalation of conflict (except in situations of abuse, potential violence, or bullying).

How to express negative emotions face-to-face:

• Assert your needs: To assert your needs, ask yourself:
  
• Write a script: Talk about what angered you (again in a clear and objective way). Tell the person how you feel, using "I feel" and "I think" statements. State your needs and what you want as clearly and specifically as possible. Finally, mention how the person will benefit from doing what you need. For instance, it might make your relationship stronger or help you reduce conflict. In addition, think about what compromises you are willing to make if the other person cannot or will not give you everything you want. And be sure to practice your script. Anger is a valuable emotion--even though we tend to see it as a problem, anger is actually instructive. What deems it destructive or instructive is what we do with our anger. When we express our needs calmly and without judgment, we show respect to others and to ourselves and maybe we even get our needs met.
• Use a non-aggressive tone: People are more likely to listen and respond calmly to you when you approach them calmly and respectfully. Avoid raising your voice or being aggressive. Watching yourself in the mirror or recording yourself as you express your anger also helps you get a better sense of your tone and demeanor.
• Use non-judgmental language: Judgmental language includes words such as "bad," "wrong," "jerk," or "selfish." These words are inherently subjective and only fuel arguments. Use facts--people are more likely to respond when being told "When you said I was lazy, I felt hurt," it's very different from telling them "You were a jerk last night." When you are talking to someone, describe what angered you in a neutral way, rather than judging the person as "rude" or "mean". Objectively, describe what that person said or did and how it made you feel.