Just a string
string
(comment)
()@example.com
fred(&)barny@example.com
fred\ barny@example.com
Abigail <abi gail @ example.com>
Abigail <abigail(fo(o)@example.com>
Abigail <abigail(fo)o)@example.com>
"Abi"gail" <abigail@example.com>
abigail@[exa]ple.com]
abigail@[exa[ple.com]
abigail@[exaple].com]
abigail@
@example.com
phrase: abigail@example.com abigail@example.com ;
