previous i used Google Workspace for sending and receiving emails for my domain.
Now i used Cloudflare E-Mail Beta service and work properly.
My small suggestion:
If user set option “catch all” - please display the question
what rule the user wants.
Default rule “DROP” is incomprehensible to less advanced people.
SPF TXT Record - If the user is using gmail SMTP for sending mail, the spf record must be different.
v=spf1 include:_spf.google.com include:_spf.mx.Cloudflare.net ~all
Thank you, Cloudflare - good job.