Email on webserver not working corretly

Hello everybody,

I am trying to make sure that when someone fills in and sends a contact from on my wordpress site that the email get send but i get this error in my logs:

Mar 2 13:31:02 localhost postfix/pickup[4965]: A69A017A325: uid=1007 from=
Mar 2 13:31:02 localhost postfix/cleanup[5089]: A69A017A325: message-id=IOZVowv9Di54eTsii0bdKcbIMj4xkb8Ysgu5Ofc6FNc@www.technolableiden.nl
Mar 2 13:31:02 localhost postfix/qmgr[4966]: A69A017A325: from=techn8401@technolableiden.nl, size=2135, nrcpt=1 (queue active)
Mar 2 13:31:02 localhost postfix/pickup[4965]: AD4FC17A327: uid=1007 from=
Mar 2 13:31:02 localhost postfix/cleanup[5089]: AD4FC17A327: message-id=CpboKntmyTwa4fc8XJxxhf28W0t6U4zOLgpOEutGs@www.technolableiden.nl
Mar 2 13:31:02 localhost postfix/pipe[5092]: A69A017A325: to=thomas@technolableiden.nl, relay=dovecot, delay=0.04, delays=0.02/0/0/0.02, dsn=5.1.1, status=bounced (user unknown)
Mar 2 13:31:02 localhost postfix/qmgr[4966]: AD4FC17A327: from=techn8401@technolableiden.nl, size=910, nrcpt=1 (queue active)
Mar 2 13:31:02 localhost postfix/cleanup[5089]: AFC3F17A328: message-id=20220302133102.AFC3F17A328@technolableiden.nl
Mar 2 13:31:02 localhost postfix/bounce[5098]: A69A017A325: sender non-delivery notification: AFC3F17A328
Mar 2 13:31:02 localhost postfix/qmgr[4966]: A69A017A325: removed
Mar 2 13:31:02 localhost postfix/qmgr[4966]: AFC3F17A328: from=<>, size=4053, nrcpt=1 (queue active)
Mar 2 13:31:02 localhost postfix/pickup[4965]: B579417A326: uid=1007 from=
Mar 2 13:31:02 localhost postfix/pipe[5092]: AD4FC17A327: to=thomas@technolableiden.nl, relay=dovecot, delay=0.04, delays=0.02/0/0/0.02, dsn=5.1.1, status=bounced (user unknown)

By the way I just resently installed the server and copied the files en dns records.

Thanks in advance.