Are emotional outbursts good for mental health?

No outbursts: Emotional outbursts are often a reflection of an inability to control one's impulses and/or an inability to regulate one's emotional responsiveness. While a person may feel a sense of relief from having "vented" or got it out of my system", it generally can be harmful to one's relationships. It also could be a sign of underlying anxiety issues and/or anger issues that are not being managed.

It depends: It depends on what is meant by "emotional outbursts." sometimes people need to know the intensity and direction of your emotions -- like when someone's trying to harm you and you're screaming "no!" in ongoing relationships, it's healthier to find safe ways to discharge anger, aggression, etc until you decide how you want to deal with the person & situation. Our words & actions have after-effects.

Journaling is better: It appears that freud was wrong about catharsis. Our emotions don't work like a hydraulic system or steam engine that needs to relieve pressure from time to time to remain healthy. But, positive communication/connecting is good. Also, studies have shown that writing about emotional distress tends to be more beneficial than venting. Focusing on causes, insight, and understanding can help.