It appears that Wietse Venema <postfix-users@postfix.org> said:
>According to Exim documentation (link below) the '!' and '%' are
>not special in email addresses, so we know that at least it does
>not appear to break legitimate usage.
Technically, that is correct. According to the local-part syntax in RFCs 5321
and 5322,
you can use all these characters, and also dots that are not at the beginning
or end:
atext = ALPHA / DIGIT / ; Printable US-ASCII
"!" / "#" / ; characters not including
"$" / "%" / ; specials. Used for atoms.
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
On the other hand, if you try to use addresses that contain ! or % you will be
in endless pain, because MTAs all over the world treat them as attempts to do
relaying and reject them.
I would go back and ask what problem they are trying to solve, because this
probably
is not the right way to solve it.
R's,
John
