It is a common mistake among Dutch people to capitalize "u." This is not technically correct; the only time you would capitalize it would be if you are addressing a deity. Implying someone's a deity might be taking it a bit too far.
- u = you (formal)
- uw = your (formal)
- alstublieft = please
- meneer = Mr. / Sir
- mevrouw = Mrs./Ms. / Ma'am
- dank u wel = thank you very much (formal)
Duolingo Lesson: www.duolingo.com/skill/dn/Formal