The domain owner is no longer using the mailbox address I used when I register their domain a few years ago. The mailbox domain name, however, is unchanged. So I went to edit the registration details in order to comply with ICAAN rules that the contact email address be kept current.
But when I put in the owner's new mailbox (copied from my Outlook Express address book which for months has been successfully sending email to the domain owner) it was uncerimoniously rejected with:
"Could not save this contact record: '[email protected]' does not seem to be a valid email address."
Needless to say "Xxxx" and "Yyyy" are place holders for the new mixed case mailbox name and the original mixed case domain name.
As a further check I copy and pasted the email address from the error message into my mail client (Outlook Express) and sucessfully sent an email to the domain owner -- clearly the email address *is* valid.
It turns out Dynadot at one time tolerated more readable mixed case email addresses like "[email protected]"; but now rejects mixed case preferring lower case like "[email protected]".
May I suggest going back to permitting mixed case? For me mixed case makes it a lot easier to enter and spot errors at the user interface.