Stalw.art allowed me to create an email with spaces. Thunderbird also allowed me to send to the address, even though it has a warning symbol and says “[…] is not a valid email address”.
And to my surprise it was also delivered sucessfully.
Edit: I also wanted to see if Lemmy allowed spaced emails. It does not :(
Did you know its based on a book written as a semi self biography.
When I found out its not just sad fiction, the story hit a little harder.