Establishing clear boundaries is essential in a professional setting when dealing with difficult individuals. Boundaries protect your emotional well-being and ensure that interactions remain respectful. Clearly communicate your limits and expectations and consistently enforce them.
If a colleague frequently emails you outside of working hours with non-urgent matters, calmly express that while you are committed to your work, you need to maintain a work-life balance. Let them know you will address non-urgent issues during office hours. For this to work, you also have to make sure that as soon as it's working hours again, you are fully willing and ready to help out your colleague. This lets them know that you are not ignoring their needs but are simply setting a reasonable boundary.
Setting boundaries may be uncomfortable initially, but it’s important for maintaining a professional and respectful environment. Over time, others will learn to respect your limits, leading to more positive interactions.