When checking my box’s DNS settings at https://dnschecker.org/#MX/gideon-it.co.uk there’s a LOT of DNS servers that aren’t finding me. Some are and some aren’t.
Any ideas why this is and if it’s likely to be causing deliverability issues?
Did you change anything the last few days?
Do you use dnssec? If so, disable it, and see if the dns situation normalizes (once dns is fixed, you can re enable it). Also, while you’re logged in at your domain registrar, check if your name servers are registered correctly.
Yes, this will impact deliverability.