Why would a personal domain need this? A personal domain will usually
only have one user, who presumably knows what mail servers they're using.
Maybe it is my mis-use of "personal". I mean any domain not owned by large
companies.
Also I think many people who buy domains for personal use, do get *(_at_)domain
mailbox. It is sort of a super feature that ISPs can offer at no extra cost.
Maybe I am wrong. But certainly many of the millions of domains have
*(_at_)domain mailbox and this is a big hole for *EXISTENT* sender address
email forgery.
Thanks,
Shelby