Ordrenummer primær should be its own table, with one record that has a key of 643211 and two fields for Name and Mail.
The field Ordrenummer primær in your existing table, Ordreliste restorde, shouldn't be a text field, it should be a "Link to another record" field pointed at your new table. Then you could bring Name and Mail over as loopkups.
That way you only have to define the name/mail for 643211 and it will automatically show up everytime 643211 is linked.
Lookup Field basics video: https://www.youtube.com/watch?v=chLX3zc6fCU
Linked Record Field documentation: https://support.airtable.com/docs/linking-records-in-airtable
Lookup Field documentation: https://support.airtable.com/docs/lookup-field-overview