Normally we use
sehr geehrte/geehrter for addressing the persons according to gender.
How can we address a
company/department/institute in a professional email?
You would say
because as you noticed it's hard to target your salutation towards one person when you're writing to a company or group. This phrase roughly translates to the English expression
Recently, also generic descriptions can be found. In advertisement letters, you are adressed as
if the style of conversation is deliberately casual, you can adress a company by
But bear in mind, that you should always use personal names if possible.