If you’re using mail.feesimpleestates.co.uk as outgoing (SMTP), that DNS record is unproxied and correct. Furthermore, your MX record point to dervy.hostns.io and SPF record exists as "v=spf1 ip4:81.xx.xxx.xx +a +mx +include:relay.mailchannels.net -all".
I am not sure which email service you’re using to sent out emails, however since A feesimpleestates.co.uk is proxied and , you might need to modify your SPF.
However:
Seems like you are having some kind of an email filtering/service in front to protect your mailbox as well?
If you’re trying to use [email protected] which is your Custom email address for Email Routing feature, unfortunately you cannot sent out emails with such feature enabled.
Either your own email service provider or only Email Routing, which acts as an email forwarder to your private mailbox such as from [email protected] to [email protected].
I am now getting the following -
Contact your hosting provider letting them know your web server is not completing requests. An Error 522 means that the request was able to connect to your web server, but that the request didn’t finish. The most likely cause is that something on your server is hogging resources. Additional troubleshooting information here.