This really feels to me like a “oh crap somebody put this email address on
10,000 pieces of customer correspondence and now we have to support it” problem.
It’s about the only excuse I would consider valid.
Sent from my iPhone
> On Mar 25, 2021, at 19:00, John Levine <jo...@iecc.com> wrote:
>
> 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
