Hi @geertje van vossole ,
Good morning and thank you for your question! First of all, I would highly recommend removing the email address on your question due to PII compliance.
Second, I would suggest posting your question on https://learn.microsoft.com/en-us/answers/tags/9/m365 for Microsoft 365 Accounts and if it a personal account, please go to this article https://support.microsoft.com/en-us/office/how-to-get-support-for-outlook-com-f5482a98-616c-4d44-b7c5-8aaaadf5c11a.
Typically, for cannot received or send messages, it is either related to the capacity of your mailbox (storage), inbox rule, or transport rule (if M365 account). If you are under a Microsoft 365 tenant, I also highly suggest to speak to your admin first for them to do message trace and investigate the routing of your emails.
I hope I was able to answer your question, if it is, please do not forget to Upvote and Accept as answer if this reply is helpful.
Have a great day ahead! 😊