Capitalisation of “wie” in “Wie geht’s?” and “ich” right after salutation

Question

I’ve heard conflicting views on this one from German speakers. Which is correct (in an email, for example):

Wie geht’s?

or

wie geht’s?

Similarly, for sentences starting with ich: One of my friends tells me that it should not be capitalized (even though it is the start of a sentence). When else is this rule true?

Answer 1

You start sentences always with a capital letter.

In this example:

Hallo Andreas,

wie geht es dir?

you do not start a new sentence, therefore you are not supposed to use a capital letter.