Edit: Read the comments too, mandarin2010 gave some great input
I know judging by the posts on this sub that this is a little late for a few Swiss DNM users. However, I have recieved some advice on this sub that wasn't 100% suitable for Switzerland, which is why I want to put this out there.
If you recieved a Vorladung, you have to go. You cannot skip it, you can call and move it if you can't attend on the specified date(don't admit anything when calling them, they will try to get you even here)
Once you're in the police station you should just try to act natural. You can be a little nervous, after all you have no idea why you got this Vorladung. Your goal is to play absolutely naive. Be nice, try wearing acceptable clothes, think twice before you talk and listen to what your personal police man they gave you is saying.
Deny everything I can't stress this enough!
You've never touched drugs, didn't even try anything. You don't drink, don't smoke weed, nothing.
You are allowed to lie in these conversations (in front of the judge you aren't and don't lie about personal information, think). To pressure you they will say they could test you "right now". Say you don't want that and you'd like to move on to the interview. They'll show you pictures of the drugs, ask you if you've been to certain countries or know people and a lot of other stuff. You don't know a thing about anything that has to do with your case (hold back your answer when asked about where you've been).
Even if they don't get you for the parcel they will get you for admitted consumption. If you say you've been smoking weed 6 times a year for 8 years, they'll add it up and get you for that amount. They also inform the Swiss drivers licence place (I forgot what it's called in english) and maybe take away your licence if the amount is enough.
If you deny everything the case should be forwarded to the statejudge.
At this point you'll just have to wait. Maybe they will ask you to go to the statejudge, maybe you'll get a fine. In both cases, get a lawyer. Tell him to either fight the fine and say you are 100%, absolutely fucking innocent or in the other case let him join you to go to the statejudge.
It will take a while but it should play out alright. If everything works out as it should you'll someday get the message that your charges have been dropped and they'll give you some money for the lawyer you needed.
Of course this probably depends on the amount you've ordered. If you know it's a high amount I would strongly advise to lawyer up.
I think that's enough text. I hope I can help at least one lost soul.
Did the police ask for your Computer? How much Did you order, of what and from where? How many packages did your order before this?