1.If it's a small thing, say it over the phone, otherwise it looks too official and can cause unnecessary worry.
在电话里批评只是小事一桩，在邮件则显得过于正式，使人忧心忡忡。
2.We usually excessively look for trouble, unnecessary worry.
我们常常过多地自寻烦恼，杞人忧天。
3.You should avoid unnecessary worry.
你应该避免不必要的担忧。
4.You've caused us all a lot of unnecessary worry.
你给我们大家带来了不必要的担心。