Route53 DNS records stopped resolving
When I lookup your domain thuijls.net on MXToolBox I get the following messageL

Dns record not found

They explain this to mean:


  More Information About Dns Record Published
  We did not find a SPF (TXT) record for the domain. Either you are using the deprecated type "SPF" record (in which case you will see a warning message for this alongside this message) or no record exists.
  
  For a SPF record to be valid, it must at least contain v=spf1


A TXT lookup for thuijls.net yeilds: 

Type   Domain Name     TTL     Record
TXT    thuijls.net     5 min   v=spf1 include:spf.messagingengine.com ?all

The problem is the ?all - you probably copy-pasted this from somewhere and the (non-standard) hyphen became a question mark.

Edit your TX record to read v=spf1 include:spf.messagingengine.com -all and all will be good.

Then you can add a 2nd TXT entry for your  "protonmail-verification-da....." setting.