Thank you,
I enabled the DNSSEC on Cloudflare and the website is back up.
I noticed there are 2 more DNSSEC entries on my registrar.
Are they now obsolete?
Can I delete them?, or might they have something to do with our mail server?
Those records will be for your previous nameservers. You might want to keep them for now in case you need to switch back for any reason, otherwise they can be deleted.