@elenio You can do this one of two ways:

1. Create a Segment of users that exclude @marketplace.amazon.com email addresses.
2. Create a Segment of users that are only @marketplace.amazon.com email addresses, and exclude them when you send your campaign.

Here’s a quick screenshot of this:

Marketing Segment Excluding Amazon Emails

Segment of Amazon Emails 

If you go with method #1, then you can just use that segment for all Campaigns and it will exclude Amazon emails automatically.  

If you go with method #2, then you have to make sure to exclude those emails every time you send a campaign. The benefit of this is you will have the option, for whatever reason, to use that Segment separately as an audience to send emails to - or if some campaigns (that are allowed by Amazon) you can choose to not exclude them. 

I imagine method #1 is more practical, and you can always create the segment for Amazon emails should you ever need to send ot them separately.

Hope this helps! 

thanks a lot. will go with 1 :)