Recently I added a DKIM record to my DNS settings, but according to this website https://dkimvalidator.com/ no DKIM signature could be found. I’m trying to send an email from the following domain: huurbuur.nl with a mailserver from Transip.
Zoho Toolkit provides a range of tools including Run checks which will check DKIM (need to enter the selector name.) You can also do this using the CLI