Hello @fchopo and @KimBim
Thanks to both of you for replying so quickly!
Seems like I did not explain my case clear enough, sorry for that!
So the big array does not contain unique names. Many people appear several times as they have many tasks.
Therefore, I am using the union function inside the apply to each which then only contains the emails.
[
{
"Name": "Bob",
"Email": "bob@mailexample.com",
"Task": "Prepare the Excel sheet",
"Importance": "High"
},
{
"Name": "Will",
"Email": "will@mailexample.com",
"Task": "Update the presentation",
"Importance": "Low"
},
{
"Name": "Bob",
"Email": "bob@mailexample.com",
"Task": "Set up a meeting",
"Importance": "Low"
}
]
This example shows that Bob has two tasks.
So outside the apply to each I have a select collecting all emails from that array as this is the unique identifier.
As I need to only send one mail per user, I need a union, which is what is used within the apply to each.
In the following screenshot you can see the working flow.
FilterArticles contains all objects
Select Email filter out the email addresses ob the big array
union within the apply to each outputs the unique addresses
FilterMailCheck compares the big array with the current item
HTML Table pulls additional information which is shown in the email
All of this works.
The only thing missing is the user name which I would like to use to personalize the Mail 🙂

I hope it is better explained now, please excuse the confusion.
Kind regards
Markus